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Excitation energy after a smooth quench in a Luttinger liquid
Low-energy physics of quasi-one-dimensional ultracold atomic gases is often described by a gapless Luttinger liquid (LL). It is nowadays routine to manipulate these systems by changing their parameters in time but, no matter how slow the manipulation is, it must excite a gapless system. We study a smooth change of parameters of the LL (a smooth ''quench'') with a variable quench time and find that the excitation energy decays with an inverse power of the quench time. This universal exponent is -2 at zero temperature and -1 for slow enough quenches at finite temperature. The smooth quench does not excite beyond the range of validity of the low-energy LL description.
Dziarmaga, Jacek; Tylutki, Marek [Institute of Physics and Center for Complex Systems Research, Jagiellonian University, Reymonta 4, PL-30-059 Krakow (Poland)
Luttinger Model and Luttinger Liquids
NASA Astrophysics Data System (ADS)
The Luttinger model owes its solvability to a number of peculiar features, like its linear relativistic dispersion relation, which are absent in more realistic fermionic systems. Nevertheless according to the Luttinger liquid conjecture a number of relations between exponents and other physical quantities, which are valid in the Luttinger model, are believed to be true in a wide class of systems, including tight binding or jellium one-dimensional fermionic systems. Recently a rigorous proof of several Luttinger liquid relations in nonsolvable models has been achieved; it is based on exact Renormalization Group methods coming from Constructive Quantum Field Theory and its main steps will be reviewed below.
Mastropietro, Vieri
NASA Astrophysics Data System (ADS)
The effect of long-ranged Coulomb interaction on the low energy properties (momentum distribution function, density of states, electron spectral function, and 4kF correlation function) of one-dimensional electron systems is determined theoretically. Over a wide, physically relevant energy range the behavior is found to be well described by the conventional, short-ranged interacting, Luttinger liquid results, with a scale-dependent effective exponent. An accurate empirical formula for the effective exponent is presented. We also discuss the qualitative line shape of the electron spectral function. (D. W. Wang, A. J. Millis, and S. Das Sarma, cond-mat/0010241 (2000))
Wang, Daw-Wei; Millis, Andrew J.; Das Sarma, S.
Luttinger-liquid behaviour in carbon nanotubes
NASA Astrophysics Data System (ADS)
Electron transport in conductors is usually well described by Fermi-liquid theory, which assumes that the energy states of the electrons near the Fermi level EF are not qualitatively altered by Coulomb interactions. In one-dimensional systems, however, even weak Coulomb interactions cause strong perturbations. The resulting system, known as a Luttinger liquid, is predicted to be distinctly different from its two- and three-dimensional counterparts. For example, tunnelling into a Luttinger liquid at energies near the Fermi level is predicted to be strongly suppressed, unlike in two- and three-dimensional metals. Experiments on one-dimensional semiconductor wires, have been interpreted by using Luttinger-liquid theory, but an unequivocal verification of the theoretical predictions has not yet been obtained. Similarly, the edge excitations seen in fractional quantum Hall conductors are consistent with Luttinger-liquid behaviour, , but recent experiments failed to confirm the predicted relationship between the electrical properties of the bulk state and those of the edge states. Electrically conducting single-walled carbon nanotubes (SWNTs) represent quantum wires that may exhibit Luttinger-liquid behaviour, . Here we present measurements of the conductance of bundles (`ropes') of SWNTs as a function of temperature and voltage that agree with predictions for tunnelling into a Luttinger liquid. In particular, we find that the conductance and differential conductance scale as power laws with respect to temperature and bias voltage, respectively, and that the functional forms and the exponents are in good agreement with theoretical predictions.
Bockrath, Marc; Cobden, David H.; Lu, Jia; Rinzler, Andrew G.; Smalley, Richard E.; Balents, Leon; McEuen, Paul L.
Theory of Nonlinear Luttinger Liquids
NASA Astrophysics Data System (ADS)
We developed a generalization of the Luttinger liquid theory which allowed us to consider threshold singularities in the momentum-resolved dynamic response functions at arbitrary momenta (i.e., far away from the Fermi points). The main difficulty the new theory overcomes is the accounting for a generic non-linear dispersion relation of quantum particles which form the liquid. We derive an effective ``quantum impurity'' Hamiltonian which adequately describes the dynamics of the system at the near-threshold energies. The phenomenological theory for the constants of such Hamiltonian is built; it expresses the constants in terms of other measurable properties (energy spectra of the excitations) of the liquid. One of the most important dynamic correlation functions we consider is the momentum-resolved electron spectral function at arbitrary momenta. The spectral function is directly measurable in tunneling experiments. It is singular at the spectrum of the lowest-energy excitation branch. In the absence of spin polarization, this is the branch of spinon excitations. The derivation of the phenomenological relations for the threshold exponent uses the SU(2) and Galilean invariance of the electron liquid. We also consider in detail the case of single-species fermions, which adequately describes the fully spin-polarized electron gas [1]. The theory of threshold exponents is valid at arbitrary wave vectors k, including the vicinities of Fermi points �kF. There, the exponents approach universal values [2] which depend only on the Luttinger liquid parameter K. Remarkably, the found exponents differ from the predictions of the conventional linear Luttinger liquid theory. The deviations from that theory though are confined to the region close to the threshold; while being wide away from the Fermi points, the width of that region scales as |k�kF|^3 at k->�kF in the absence of spin polarization, and as (k�kF)^2 for polarized electrons. [4pt] [1] A. Imambekov, L.I. Glazman, Phys. Rev. Lett., 102, 126405 (2009)[0pt] [2] A. Imambekov, L.I. Glazman, Science, 323, 228 (2009)
Glazman, Leonid
Long Time Correlations of Nonlinear Luttinger Liquids
NASA Astrophysics Data System (ADS)
An overview is given of the limitations of Luttinger liquid theory in describing the real time equilibrium dynamics of critical one-dimensional systems with nonlinear dispersion relation. After exposing the singularities of perturbation theory in band curvature effects that break the Lorentz invariance of the Tomonaga-Luttinger model, the origin of high frequency oscillations in the long time behaviour of correlation functions is discussed. The notion that correlations decay exponentially at finite temperature is challenged by the effects of diffusion in the density-density correlation due to umklapp scattering in lattice models.
Pereira, Rodrigo G.
Instabilites des Liquides de Luttinger Couples Cinetiquement
NASA Astrophysics Data System (ADS)
On presente une nouvelle formulation integrale fonctionnelle qui permet l'etude du crossover dimensionnel a une et a deux particules des systemes de liquides de Luttinger couples par une integrale de saut interchai ne. Cette formulation constitue en fait une methode generale permettant de generer systematiquement une theorie des perturbations lorsque le systeme non-perturbe est decrit par un hamiltonien a N-corps et que la perturbation est un operateur a un corps. Dans un premier temps, le formalisme est introduit dans un contexte general et illustre par quelques exemples d'applications. En second lieu, les proprietes du gaz d'electrons unidimensionnel en interaction, ou liquide de Luttinger, sont resumees. Ensuite, le formalisme de la fonctionnelle de Landau-Ginzburg fermionique est applique au probleme de la stabilite du systeme de liquides de Luttinger couples cinetiquement. On considere successivement la stabilite a la coherence a une et a deux particules ainsi que l'influence du champ magnetique. Dans le cas du faible couplage, le systeme presente une instabilite associee a l'etablissement de la coherence a une particule dans la direction transversale aux chai nes et cela, aussi petite que soit l'amplitude de saut dans la direction transversale. Le systeme evolue alors vers un regime ou le mouvement dans la direction transversale aux chaines est un mouvement de bande coherent. L'expression de la temperature ou se produit ce deconfinement electronique est etablie dans le contexte general ou les vitesses associees aux degres de liberte de spin et de charge different et ou les exposants anormaux sont non-nuls. Nous presentons ensuite un resultat strictement exact pour le systeme de liquides de Luttinger couples par une integrale de saut transversal dans la limite ou la portee de ce saut tend vers l'infini. Dans cette limite, nous obtenons l'expression exacte du propagateur electronique et de la temperature de crossover a une particule. Enfin, dans le regime du couplage fort, on montre que le systeme presente une instabilite due a la propagation des correlations a deux particules dans la direction transversale aux chai nes. Comme dans le cas a une particule, ce crossover dimensionnel a deux particules est etudie dans le contexte general ou les vitesses de spin et de charge different et ou les exposants anormaux sont quelconques. On donne la temperature ou les correlations a deux particules commencent a s'etendre dans la direction transversale aux chai nes.
Boies, Daniel
Emergent ``super-solitons'' following an interaction strength quantum quench across a Luttinger liquid-Mott insulating phase boundary
Rapid progress in cold atom experiments has motivated the study of non-equilibrium many-body dynamics following a sudden deformation of the system Hamiltonian (a ``quantum quench''). Here, we consider the dynamics of localized excitations produced via a quench across a quantum phase boundary separating critical Luttinger liquid and gapped Mott insulating states. Our initial liquid ground state is labeled by a
Matthew Foster; Emil Yuzbashyan
Tunable Nonequilibrium Luttinger Liquid Based on Counterpropagating Edge Channels
NASA Astrophysics Data System (ADS)
We investigate the energy transfer between counterpropagating quantum Hall edge channels (ECs) in a two-dimensional electron system at a filling factor of ? =1. The ECs are separated by a thin impenetrable potential barrier and Coulomb coupled, thereby constituting a quasi-one-dimensional analogue of a spinless Luttinger liquid (LL). We drive one, say hot, EC far from thermal equilibrium and measure the energy transfer rate P into the second, cold, EC using a quantum point contact as a bolometer. The dependence of P on the drive bias indicates a breakdown of the momentum conservation, whereas P is almost independent of the length of the region where the ECs interact. Interpreting our results in terms of plasmons (collective density excitations), we find that the energy transfer between the ECs occurs via plasmon backscattering at the boundaries of the LL. The backscattering probability is determined by the LL interaction parameter and can be tuned by changing the width of the electrostatic potential barrier between the ECs.
Prokudina, M. G.; Ludwig, S.; Pellegrini, V.; Sorba, L.; Biasiol, G.; Khrapai, V. S.
Fractionalized wave packets from an artificial Tomonaga-Luttinger liquid.
The model of interacting fermion systems in one dimension known as a Tomonaga-Luttinger liquid (TLL) provides a simple and exactly solvable theoretical framework that predicts various intriguing physical properties. Evidence of a TLL has been observed as power-law behaviour in electronic transport on various types of one-dimensional conductor. However, these measurements, which rely on d.c. transport involving electron tunneling processes, cannot identify the long-awaited hallmark of charge fractionalization, in which an injection of elementary charge e from a non-interacting lead is divided into the non-trivial effective charge e* and the remainder, e-e* (refs�6, 7, 8). Here, we report time-resolved transport measurements on an artificial TLL composed of coupled integer quantum Hall edge channels, in which we successfully identify single charge fractionalization processes. A wave packet of charge q incident from a non-interacting region breaks up into several fractionalized charge wave packets at the edges of the artificial TLL, from which transport eigenmodes can be evaluated directly. These results are informative for elucidating the nature of TLLs and low-energy excitations in the edge channels. PMID:24509659
Kamata, H; Kumada, N; Hashisaka, M; Muraki, K; Fujisawa, T
Attractive Tomonaga-Luttinger Liquid in a Quantum Spin Ladder
NASA Astrophysics Data System (ADS)
We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1?T1/2K-1, which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1
Jeong, M.; Mayaffre, H.; Berthier, C.; Schmidiger, D.; Zheludev, A.; Horvati?, M.
Some Experimental Tests of Tomonaga-Luttinger Liquids
NASA Astrophysics Data System (ADS)
The Tomonaga-Luttinger-Liquid (TLL) has been the cornerstone of our understanding of the properties of one dimensional systems. This universal set of properties plays in one dimension, the same role than Fermi liquid plays for the higher dimensional metals. I will give in these notes an overview of some of the experimental tests that were made to probe such TLL physics. In particular I will detail some of the recent experiments that were made in spin systems and which provided remarkable quantitative tests of the TLL physics.
Giamarchi, T.
Correlated sequential tunneling in Tomonaga-Luttinger liquid quantum dots
NASA Astrophysics Data System (ADS)
We investigate tunneling through a quantum dot formed by two strong impurites in a spinless Tomonaga-Luttinger liquid. Upon employing a Markovian master equation approach, we compute the linear conductance due to sequential tunneling processes. Besides the previously used lowest-order Golden Rule rates describing uncorrelated sequential tunneling (UST) processes, we systematically include higher-order correlated sequential tunneling (CST) diagrams within the standard Weisskopf-Wigner approximation. We provide estimates for the parameter regions where CST effects are shown to dominate over UST. Focusing mainly on the temperature dependence of the conductance maximum, we discuss the relation of our results to previous theoretical and experimental results.
Thorwart, M.; Egger, R.; Grifoni, M.
Singular responses of spin-incoherent Luttinger liquids.
When a local potential changes abruptly in time, an electron gas responds by shifting to a new state which at long times is orthogonal to the one in the absence of the local potential. This is known as Anderson's orthogonality catastrophe and it is relevant for the so-called x-ray edge or Fermi-edge singularity, and for tunneling into an interacting one-dimensional system of fermions. It often happens that the finite frequency response of the photon absorption or the tunneling density of states exhibits a singular behavior as a function of frequency: [Formula: see text], where ?(th) is a threshold frequency and ? is an exponent characterizing the singular response. In this review singular responses of spin-incoherent Luttinger liquids are reviewed. Such responses most often do not fall into the familiar form above, but instead typically exhibit logarithmic corrections and display a much higher universality in terms of the microscopic interactions in the theory. Specific predictions are made, the current experimental situation is summarized and key outstanding theoretical issues related to spin-incoherent Luttinger liquids are highlighted. PMID:21825474
Fiete, Gregory A
One-dimensional fermions with neither Luttinger-liquid nor Fermi-liquid behavior.
It is well known that, generically, one-dimensional interacting fermions cannot be described in terms of a Fermi liquid. Instead, they present a different phenomenology, that of a Tomonaga-Luttinger liquid: the Landau quasiparticles are ill defined, and the fermion occupation number is continuous at the Fermi energy. We demonstrate that suitable fine tuning of the interaction between fermions can stabilize a peculiar state of one-dimensional matter, which is dissimilar to both Tomonaga-Luttinger and Fermi liquids. We propose to call this state a quasi-Fermi liquid. Technically speaking, such a liquid exists only when the fermion interaction is irrelevant (in the renormalization group sense). The quasi-Fermi liquid exhibits the properties of both a Tomonaga-Luttinger liquid and a Fermi liquid. Similar to a Tomonaga-Luttinger liquid, no finite-momentum quasiparticles are supported by the quasi-Fermi liquid; on the other hand, its fermion occupation number demonstrates a finite discontinuity at the Fermi energy, which is a hallmark feature of a Fermi liquid. A possible realization of the quasi-Fermi liquid with the help of cold atoms in an optical trap is discussed. PMID:24679312
Rozhkov, A V
Anomalous chiral Luttinger liquid behavior of diluted fractionally charged quasiparticles
NASA Astrophysics Data System (ADS)
Fractionally charged quasiparticles in edge states, are expected to condense to a chiral Luttinger liquid (CLL). We studied their condensation by measuring the conductance and shot noise due to an artificial backscatterer embedded in their path. At sufficiently low-temperatures backscattering events were found to be strongly correlated, producing a highly nonlinear current-voltage characteristic and a nonclassical shot noise�both are expected in a CLL. When, however, the impinging beam of quasiparticles was made dilute, either artificially via an additional weak backscatterer or by increasing the temperature, the resultant outgoing noise was classical, indicating the scattering of independent quasiparticles. Here, we study in some detail this surprising crossover from correlated particle behavior to an independent behavior, as a function of beam dilution and temperature.
Chung, Y. C.; Heiblum, M.; Oreg, Y.; Umansky, V.; Mahalu, D.
Time-resolved charge fractionalization in inhomogeneous Luttinger liquids
NASA Astrophysics Data System (ADS)
The recent observation of charge fractionalization in single Tomanga-Luttinger liquids (TLLs) [H. Kamata et al., Nat. Nanotechnol. 9, 177 (2014), 10.1038/nnano.2013.312] opens new routes for a systematic investigation of this exotic quantum phenomenon. In this Rapid Communication we perform measurements on two adjacent TLLs and put forward an accurate theoretical framework to address the experiments. The theory is based on the plasmon scattering approach and can deal with injected charge pulses of arbitrary shape in TLL regions. We accurately reproduce and interpret the time-resolved multiple fractionalization events in both single and double TLLs. The effect of intercorrelations between the two TLLs is also discussed.
Perfetto, E.; Stefanucci, G.; Kamata, H.; Fujisawa, T.
Light scattering in inhomogeneous Tomonaga-Luttinger liquids
NASA Astrophysics Data System (ADS)
We derive the dynamical structure factor for an inhomogeneous Tomonaga-Luttinger liquid (TLL) as can be formed in a confined strongly interacting one-dimensional gas. In view of the current experimental progress in the field, we provide a simple analytic expression for the light-scattering cross section, requiring only the knowledge of the density dependence of the ground-state energy as it can be extracted, e.g., from exact or quantum Monte Carlo (QMC) techniques and a Thomas-Fermi description. We apply the result to the case of one-dimensional quantum bosonic gases with dipolar interaction in a harmonic trap, using an energy functional deduced from QMC computations. We find a universal scaling behavior peculiar to the TLL, a signature that can be probed eventually by Bragg spectroscopy in experimental realizations of such systems.
Orignac, E.; Citro, R.; de Palo, S.; Chiofalo, M.-L.
Particle hole symmetric Luttinger liquids in a quantum Hall circuit
NASA Astrophysics Data System (ADS)
We report finite-bias differential conductance measurements through a split-gate constriction in the integer quantum Hall regime at ?=1. Both enhanced and suppressed zero-bias inter-edge backscattering can be obtained in a controllable way by changing the split-gate voltage. This behavior is interpreted in terms of local charge depletion and particle-hole symmetry. We discuss the relevance of particle-hole symmetry in connection with the chiral Luttinger model of edge states.
Roddaro, Stefano; Perinetti, Umberto; Pellegrini, Vittorio; Beltram, Fabio; Pfeiffer, Loren N.; West, Ken W.
Electron spin resonance signal of Luttinger liquids and single-wall carbon nanotubes.
A comprehensive theory of electron spin resonance (ESR) for a Luttinger liquid state of correlated metals is presented. The ESR measurables such as the signal intensity and the linewidth are calculated in the framework of Luttinger liquid theory with broken spin rotational symmetry as a function of magnetic field and temperature. We obtain a significant temperature dependent homogeneous line broadening which is related to the spin-symmetry breaking and the electron-electron interaction. The result crosses over smoothly to the ESR of itinerant electrons in the noninteracting limit. These findings explain the absence of the long-sought ESR signal of itinerant electrons in single-wall carbon nanotubes when considering realistic experimental conditions. PMID:18851238
D�ra, B; Gul�csi, M; Koltai, J; Z�lyomi, V; K�rti, J; Simon, F
Luttinger liquid with strong spin-orbital coupling and Zeeman splitting in quantum wires
We study a one-dimensional interacting electron gas with the strong Rashba spin-orbit coupling and Zeeman splitting in a quantum well. A bosonization theory is developed for this system. The tunneling current may deviate from a simple power law which is that in an ordinary Luttinger liquid. The microscopic interacting coupling and the spin-orbital parameter may be measured by varying the
Yue Yu; Yuchuan Wen; Jinbin Li; Zhaobin Su; S. T. Chui
Particle-Hole Symmetric Luttinger Liquids in a Quantum Hall Circuit
NASA Astrophysics Data System (ADS)
We report current transmission data through a split-gate constriction fabricated onto a two-dimensional electron system in the integer quantum Hall (QH) regime. Split-gate biasing drives interedge backscattering and is shown to lead to suppressed or enhanced transmission, in marked contrast to the expected linear Fermi-liquid behavior. This evolution is described in terms of particle-hole symmetry and allows us to conclude that an unexpected class of gate-controlled particle-hole-symmetric chiral Luttinger liquids (CLLs) can exist at the edges of our QH circuit. These results highlight the role of particle-hole symmetry on the properties of CLL edge states.
Roddaro, Stefano; Pellegrini, Vittorio; Beltram, Fabio; Pfeiffer, Loren N.; West, Ken W.
Tomonaga-Luttinger liquid features in ballistic single-walled carbon nanotubes: conductance and shot noise.
We study the electrical transport properties of well-contacted ballistic single-walled carbon nanotubes in a three-terminal configuration at low temperatures. We observe signatures of strong electron-electron interactions: the conductance exhibits bias-voltage-dependent amplitudes of quantum interference oscillation, and both the current noise and Fano factor manifest bias-voltage-dependent power-law scalings. We analyze our data within the Tomonaga-Luttinger liquid model using the nonequilibrium Keldysh formalism and find qualitative and quantitative agreement between experiment and theory. PMID:17678308
Kim, Na Young; Recher, Patrik; Oliver, William D; Yamamoto, Yoshihisa; Kong, Jing; Dai, Hongjie
Luttinger liquid theory of Coulomb drag in mesoscopic rings,(Supported in part by US DOE.)
NASA Astrophysics Data System (ADS)
We develop a Luttinger liquid theory of the Coulomb drag of persistent currents, flowing in concentric mesoscopic rings, by incorporating non-linear corrections to the electron dispersion relation. We demonstrate that at low temperatures interactions between electrons in different rings generate an additional phase and thus alter the period of Aharonov-Bohm oscillations. The resulting nondissipative(A. G. Rojo and G. D. Mahan, Phys. Rev. Lett. 68) 2074 (1992). drag depends strongly on the relative parity of the electron numbers. We also show that interactions set a new temperature scale below which the linear response theory does not apply at certain values of external flux.
Shahbazyan, T. V.; Ulloa, S. E.
Exciton Dynamics in Carbon Nanotubes: From the Luttinger Liquid to Harmonic Oscillators
NASA Astrophysics Data System (ADS)
We show that the absorption spectrum in semiconducting nanotubes can be determined using the bosonization technique combined with mean-field theory and a harmonic approximation. In this framework, a multiple band semiconducting nanotube reduces to a system of weakly coupled harmonic oscillators. We also find that gaps of any size destroy the Luttinger liquid phase in single-walled carbon nanotubes and give rise to electron density fluctuations that resemble excitons built from quasiparticles. Interband processes, such as multiple exciton generation, become progressively weaker as the length to diameter ratio grows larger.
Sweeney, M. C.; Eaves, J. D.
Stability of the Tomonaga-Luttinger liquid state in gamma-irradiated carbon nanotube bundles
NASA Astrophysics Data System (ADS)
We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by 60Co ?-rays in various environments. In the current study the samples investigated were irradiated in hermetic cells, either evacuated (0.1 Pa) or filled with hydrogen or deuterium at atmospheric pressure. In situ measurements of the resistance change as a function of irradiation dose at room temperature are presented. It was found that, for all irradiation conditions, the normalized resistance versus irradiation dose demonstrates a logarithmic behaviour. A phenomenological model for the observed dependence is derived. The current-voltage characteristics of the irradiated samples were measured in the temperature range from 4.5 to 300 K using short (10 ns) electric pulses, and the results demonstrate a scaling behaviour. This scaling occurs in the universal coordinates that correspond to the Tomonaga-Luttinger liquid concept. Our results confirm the existence of the Tomonaga-Luttinger liquid phase up to room temperature in carbon nanotubes after ?-irradiation to a dose of 5 � 107 rad in vacuum, 1.7 � 107 rad in hydrogen and 1.24 � 108 rad in deuterium.
Danilchenko, B. A.; Tripachko, N. A.; Voitsihovska, E. A.; Yaskovets, I. I.; Uvarova, I. Y.; Sundqvist, B.
Stability of the Tomonaga-Luttinger liquid state in gamma-irradiated carbon nanotube bundles.
We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by (60)Co ?-rays in various environments. In the current study the samples investigated were irradiated in hermetic cells, either evacuated (0.1�Pa) or filled with hydrogen or deuterium at atmospheric pressure. In�situ measurements of the resistance change as a function of irradiation dose at room temperature are presented. It was found that, for all irradiation conditions, the normalized resistance versus irradiation dose demonstrates a logarithmic behaviour. A phenomenological model for the observed dependence is derived. The current-voltage characteristics of the irradiated samples were measured in the temperature range from 4.5 to 300�K using short (10�ns) electric pulses, and the results demonstrate a scaling behaviour. This scaling occurs in the universal coordinates that correspond to the Tomonaga-Luttinger liquid concept. Our results confirm the existence of the Tomonaga-Luttinger liquid phase up to room temperature in carbon nanotubes after ?-irradiation to a dose of 5�נ10(7)�rad in vacuum, 1.7�נ10(7)�rad in hydrogen and 1.24�נ10(8)�rad in deuterium. PMID:24172218
Danilchenko, B A; Tripachko, N A; Voitsihovska, E A; Yaskovets, I I; Uvarova, I Y; Sundqvist, B
Cluster Luttinger liquids of Rydberg-dressed atoms in optical lattices.
We investigate the zero-temperature phases of bosonic and fermionic gases confined to one dimension and interacting via a class of finite-range soft-shoulder potentials (i.e., soft-core potentials with an additional hard-core onsite interaction). Using a combination of analytical and numerical methods, we demonstrate the stabilization of critical quantum liquids with qualitatively new features with respect to the Tomonaga-Luttinger liquid paradigm. These features result from frustration and cluster formation in the corresponding classical ground state. Characteristic signatures of these liquids are accessible in state-of-the-art experimental setups with Rydberg-dressed ground-state atoms trapped in optical lattices. PMID:24182276
Mattioli, Marco; Dalmonte, Marcello; Lechner, Wolfgang; Pupillo, Guido
Intersection of two nanotubes: density of states modulated by plasmon beatings with period governed by Luttinger-liquid parameter
We study theoretically the plasmon scattering at the intersection of two metallic carbon nanotubes. We demonstrate that for a small angle of crossing, theta1, the transmission coefficient is an oscillatory function of lambda\\/theta, where lambda is the interaction parameter of the Luttinger liquid in an individual nanotube. We calculate the tunnel density of states, nu(,), as a function of energy,
Vagharsh Mkhitaryan; Yuan Fang; Jordan Gerton; Eugene Mishchenko; Mikhail Raikh
Nonmonotonic behaviors of Fano factor in double quantum dot connected with Luttinger liquid electrodes.
In this study, we discuss the behavior of the Fano factor in a double quantum dot (DQD) connected with Luttinger liquid (LL) electrodes. At the Toulouse point, we study the dependence of the Fano factor on the bias voltage, the energy level of the dots, the interdot coupling, and the asymmetry parameter. We show that the behavior of the Fano factor in a DQD is similar to that in a single quantum dot (SQD); however, it behaves nonmonotonically with bias voltage and three local extrema can occur. The condition for the occurrence of nonmonotonic behavior is determined, and it is shown that local extrema result from the mixing of the bare energy levels of the dots caused by the interdot coupling. The influence of the Klein factor on the conductance in a DQD and the limitation of the perturbation calculation for a DQD are discussed. PMID:21832386
Kawaguchi, Satoshi
Wilson ratio of a Tomonaga-Luttinger liquid in a spin-1/2 Heisenberg ladder
NASA Astrophysics Data System (ADS)
We report a comprehensive study of a strong-leg spin-1/2 ladder compound (C7H10N)2CuBr4 (DIMPY) by specific heat, magnetocaloric effect, magnetization and inelastic neutron scattering measurements. DIMPY is shown to be a perfect one-dimensional Heisenberg antiferromagnet with a spin gap=0.32 meV. Above a critical field Hc and at temperature below 1 K, the specific heat exhibits asymptotic linear-T behavior, characteristic of a Tomonaga-Luttinger liquid (TLL). In this field and temperature region, the specific heat in conjunction with the susceptibility yields the Wilson ratio RW. The result supports the relation RW=4K, where K is the TLL parameter.
Hong, Tao; Ninios, K.; Kim, Y. H.; Manabe, T.; Hotta, C.; Tremelling, G.; Herringer, S. N.; Turnbull, M. M.; Landee, C.; Kang, H.-J.; Schmidt, K. P.; Uhrig, G. S.; Chan, H. B.; Broholm, C.; Takano, Y.
Non-Fermi-Liquid Single Particle Line Shape of the Quasi-One-Dimensional Non-CDW Metal Li{sub 0.9}Mo{sub 6}O{sub 17} : Comparison to the Luttinger Liquid
We report the detailed non-Fermi-liquid (NFL) line shape of the dispersing excitation which defines the Fermi surface for quasi-one-dimensional Li{sub 0.9}Mo {sub 6}O{sub 17} . The properties of Li{sub 0.9}Mo {sub 6}O{sub 17} strongly suggest that the NFL behavior has a purely electronic origin. In relation to the theoretical Luttinger liquid line shape, we identify significant similarities, but also important differences. {copyright} {ital 1999} {ital The American Physical Society}
Denlinger, J.D.; Gweon, G.; Allen, J.W.; Schlenker, C.; Hsu, L. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)] [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States); Olson, C.G. [Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Marcus, J. [Laboratoire d`Etudes des Proprietes Electroniques des Solides--CNRS, BP166, 38042 Grenoble Cedex (France)] [Laboratoire d`Etudes des Proprietes Electroniques des Solides--CNRS, BP166, 38042 Grenoble Cedex (France)
Entanglement spectra between coupled Tomonaga-Luttinger liquids: Applications to ladder systems and topological phases
NASA Astrophysics Data System (ADS)
We study the entanglement spectrum (ES) and entropy between two coupled Tomonaga-Luttinger liquids (TLLs) on parallel periodic chains. This problem gives access to the entanglement properties of various interesting systems, such as spin ladders as well as two-dimensional topological phases. By expanding interchain interactions to quadratic order in bosonic fields, we are able to calculate the ES for both gapped and gapless systems using only methods for free theories. In certain gapless phases of coupled nonchiral TLLs, we interestingly find an ES with a dispersion relation proportional to the square root of the subsystem momentum, which we relate to a long-range interaction in the entanglement Hamiltonian. We numerically demonstrate the emergence of this unusual dispersion in a model of hard-core bosons on a ladder. In gapped phases of coupled nonchiral TLLs, which are relevant to spin ladders and topological insulators, we show that the ES consists of linearly dispersing modes, which resembles the spectrum of a single-chain TLL but is characterized by a modified TLL parameter. Based on a calculation for coupled chiral TLLs, we are also able to provide a very simple proof for the correspondence between the ES and the edge-state spectrum in quantum Hall systems consistent with previous numerical and analytical studies.
Lundgren, Rex; Fuji, Yohei; Furukawa, Shunsuke; Oshikawa, Masaki
Transport properties of topological superconductor-Luttinger liquid junctions: A real-time Keldysh approach
NASA Astrophysics Data System (ADS)
Inspired by a recent experimental observation of the zero-bias tunneling conductance in superconductor-semiconductor nanowire devices [V. Mourik , ScienceSCIEAS0036-807510.1126/science.1222360 336, 1003 (2012)], we consider here transport properties of the junctions consisting of a nanowire (Luttinger liquid) coupled to a topological superconductor characterized by the presence of Majorana zero-energy end states. The presence of the Majorana modes leads to a quantization of the zero-bias tunneling conductance at zero temperature. In order to understand this phenomenon, we have developed a framework, based on real-time Keldysh technique, which allows one to compute tunneling conductance at finite temperature and voltage in a realistic experimental setup. Our approach allows one to understand this transport phenomenon from a more general perspective by including the effect of interactions in the nanowire, which sometimes results in a drastic departure from the noninteracting predictions. Thus, our results provide a key insight for the tunneling experiments aiming at detecting Majorana particles in one-dimensional nanowire devices.
Lutchyn, Roman M.; Skrabacz, Jacob H.
Chiral Y junction of Luttinger liquid wires at strong coupling: Fermionic representation
NASA Astrophysics Data System (ADS)
We calculate the conductances of a three-terminal junction setup of spinless Luttinger liquid wires threaded by a magnetic flux, allowing for different interaction strength g3?g in the third wire. We employ the fermionic representation in the scattering state picture, allowing for a direct calculation of the linear response conductances, without the need of introducing contact resistances at the connection points to the outer ideal leads. The matrix of conductances is parametrized by three variables. For these we derive coupled renormalization group (RG) equations, by summing up infinite classes of contributions in perturbation theory. The resulting general structure of the RG equations may be employed to describe junctions with an arbitrary number of wires and arbitrary interaction strength in each wire. The fixed point structure of these equations (for the chiral Y junction) is analyzed in detail. For repulsive interaction (g,g3>0) there is only one stable fixed point, corresponding to the complete separation of the wires. For attractive interaction (g<0 and/or g3<0) four fixed points are found, the stability of which depends on the interaction strength. We confirm our previous weak-coupling result of lines of fixed points for special values of the interaction parameters reaching into the strong-coupling domain. We find new fixed points not discussed before, even at the symmetric line g=g3, at variance with the results of M. Oshikawa [J. Stat. Mech.1742-546810.1088/1742-5468/2006/02/P02008 (2006) P02008]. The pair-tunneling phenomenon conjectured by the latter authors is not found by us.
Aristov, D. N.; W�lfle, P.
Field-induced Tomonaga-Luttinger liquid phase of a two-leg spin-1/2 ladder with strong leg interactions
We study the magnetic-field-induced quantum phase transition from a gapped quantum phase that has no magnetic long-range order into a gapless phase in the spin-1/2 ladder compound bis(2,3-dimethylpyridinium) tetrabromocuprate (DIMPY). At temperatures below about 1 K, the specific heat in the gapless phase attains an asymptotic linear temperature dependence, characteristic of a Tomonaga-Luttinger liquid. Inelastic neutron scattering and the specific heat measurements in both phases are in good agreement with theoretical calculations, demonstrating that DIMPY is the first model material for an S=1/2 two-leg spin ladder in the strong-leg regime.
Kim, Y. H. [University of Florida, Gainesville; Hotta, C. [Kyoto Sangyo University; Takano, Y. [University of Florida, Gainesville; Tremelling, G. [Clark University; Turnbull, M. M. [Clark University; Landee, C. [Clark University; Kang, H.-J. [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Christensen, N. B. [Laboratory for Neutron Scattering ETHZ & PSI; Lefmann, K. [Riso National Laboratory, Roskilde, Denmark; Schmidt, K. P. [Technische Universit Dortmund, Germany; Uhrig, G. S. [Technische Universit Dortmund, Germany; Broholm, C. [Johns Hopkins University
Enhanced NMR Relaxation of Tomonaga-Luttinger Liquids and the Magnitude of the Carbon Hyperfine Coupling in Single-Wall Carbon Nanotubes
NASA Astrophysics Data System (ADS)
Recent transport measurements [Churchill et al. Nature Phys.NPAHAX1745-2473 5, 321 (2009)10.1038/nphys1247] found a surprisingly large, 2-3 orders of magnitude larger than usual C13 hyperfine coupling (HFC) in C13 enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17 004 (2010)EULEEJ0295-507510.1209/0295-5075/90/17004]. Though we find that 1/T1 is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters.
Kiss, A.; P�lyi, A.; Ihara, Y.; Wzietek, P.; Simon, P.; Alloul, H.; Z�lyomi, V.; Koltai, J.; K�rti, J.; D�ra, B.; Simon, F.
Transverse excitations in liquid Sn.
Transverse acoustic (TA) excitation modes were observed in inelastic x-ray scattering (IXS) spectra of liquid Sn. The excitation energies and widths of the TA modes are in good agreement with results of an ab initio molecular dynamics simulation. By comparing current correlation spectra between the experimental and theoretical results quantitatively, we have concluded that the TA modes can be detected experimentally through the quasi-TA branches in the longitudinal current correlation spectra. The lifetime and propagation length of the TA modes were determined to be ~0.7 ps and 0.8-1.0 nm, respectively, corresponding to the size of cages formed instantaneously in liquid Sn. PMID:23378432
Hosokawa, S; Munejiri, S; Inui, M; Kajihara, Y; Pilgrim, W-C; Ohmasa, Y; Tsutsui, S; Baron, A Q R; Shimojo, F; Hoshino, K
Elementary Excitations in Quantum Liquids.
ERIC Educational Resources Information Center
Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)
Pines, David
Transverse excitations in liquid metals
NASA Astrophysics Data System (ADS)
The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga, Cu and Fe in the Q range around 10 nm-1 using a third-generation synchrotron radiation facility, SPring-8, although these liquid metals are mostly described by a simple hard-sphere liquid. Ab initio molecular dynamics simulations clearly support this finding for liquid Ga. From the detailed analyses for the S(Q,?) spectra with good statistic qualities, the lifetime of less than 1 ps and the propagating length of less than 1 nm can be estimated for the transverse acoustic phonon modes, which correspond to the lifetime and size of cages formed instantaneously in these liquid metals. The microscopic Poisson's ratio estimated from the dynamic velocities of sound is 0.42 for liquid Ga and about -0.2 for liquid transition metals, indicating a rubber-like soft and extremely hard elastic properties of the cage clusters, respectively. The origin of these microscopic elastic properties is discussed in detail.
Hosokawa, S.; Munejiri, S.; Inui, M.; Kajihara, Y.; Pilgrim, W.-C.; Baron, A. Q. R.; Shimojo, F.; Hoshino, K.
AB2 Hubbard chains in the strong-coupling limit: Ferrimagnetism, Nagaoka and RVB states, phase separation, and Luttinger-liquid behavior
NASA Astrophysics Data System (ADS)
We present a functional-integral formalism suitable to describe the strong-coupling regime below half filling of AB2 Hubbard chains, with experimental realizations in inorganic and organic polymeric compounds. At half filling (one electron per site: ?=0 ), we obtain the long-range-ordered ferrimagnetic ground state and correctly reproduce the associated quantum nonrelativistic nonlinear ? model, with presence of topological Wess-Zumino terms, which has been also found in a coherent-state representation, restricted however to treat the case of localized spins. A fully polarized (Nagaoka) ferromagnetic state is obtained in the infinite-coupling regime near half filling, and at doping ?=1/3 (two electrons per unit cell) insulating short-range resonating-valence-bond (RVB) singlet states take place. Competition between Nagaoka and RVB mechanisms can lead to phase separation for 0<1/3 . By increasing the hole doping, a crossover regime for 1/3<2/3 anticipates the emergence of Luttinger-liquid behavior for ??2/3 . In particular, at ?=2/3 (one electron per cell) the system behaves similarly to a critical spin-1/2 antiferromagnetic linear chain. All these results find support in numerical studies both in the half filling and doped regimes.
Oliveira, M. H.; Raposo, E. P.; Coutinho-Filho, M. D.
Liquid storage tanks under vertical excitation
Until recently, the hydrodynamic effects on liquid storage tanks induced by an earthquake excitation were basically treated for the horizontal component of the earthquake. Recent studies, however, showed that the hydrodynamic effects due to the vertical component of an earthquake may be significant. In these studies the tank is assumed to be fixed at the bottom. This paper is concerned with the hydrodynamic behavior of liquid storage tanks induced by vertical earthquake input excitation. First, the fluid-tank system is treated as a fixed-base system and a simple formula is obtained for the coupled fluid-structure natural frequency. Second, additional interaction effects due to the foundation flexibility on the fluid-tank system are investigated. It is concluded that the foundation flexibility may have a significant effect on the hydrodynamic behavior of the liquid storage tanks under a vertical ground shaking.
Philippacopoulos, A.J.
Luttinger parameters of interacting fermions in one dimension at high energies
NASA Astrophysics Data System (ADS)
Interactions between electrons in one dimension are fully described at low energies by only a few parameters of the Tomonaga-Luttinger model, which is based on linearization of the spectrum. We consider a model of spinless fermions with short-range interaction via the Bethe-Ansatz technique and show that a Luttinger parameter emerges in an observable beyond the low-energy limit. A distinct feature of the spectral function, the edge that marks the lowest possible excitation energy for a given momentum, is parabolic for arbitrary momenta and the prefactor is a function of the Luttinger parameter, K.
Tsyplyatyev, O.; Schofield, A. J.
Luttinger-like parameter calculations
We have calculated the Luttinger-like parameters, used in the 8{times}8 Hamiltonian describing both conduction and valence bands, via a second-order perturbation theory that allows one to make the Lowdin renormalization valid for a set of nondegenerate energy levels. We show that the formulas given in the paper by Pidgeon and Brown [Phys. Rev. >146, 575 (1966)] are the correct ones, contrary to what is claimed in recent papers. This leads to strong discrepancies when the spin-orbit splitting is not much smaller than the band gap. For example, the ratio between the Luttinger-like parameters {tilde {gamma}}{sub 1}, calculated in the two cases, is of the order of 1.5 in GaAs, 3 in InAs, and 16 in InSb. The accuracy of the equations used by Pidgeon and Brown is also discussed.
Boujdaria, Kais; Ridene, Said; Fishman, Guy
Photoinduced excited state electron transfer at liquid/liquid interfaces.
Several aspects of the photoinduced electron transfer (ET) reaction between coumarin 314 (C314) and N,N-dimethylaniline (DMA) at the water/DMA interface are investigated by molecular dynamics simulations. New DMA and water/DMA potential energy surfaces are developed and used to characterize the neat water/DMA interface. The adsorption free energy, the rotational dynamics, and the solvation dynamics of C314 at the liquid/liquid interface are investigated and are generally in reasonable agreement with available experimental data. The solvent-free energy curves for the ET reaction between excited C314 and DMA molecules are calculated and compared with those calculated for a simple point charge model of the solute. It is found that the reorganization free energy is very small when the full molecular description of the solute is taken into account. An estimate of the ET rate constant is in reasonable agreement with experiment. Our calculations suggest that the polarity of the surface "reported" by the solute, as reflected by solvation dynamics and the reorganization free energy, is strongly solute-dependent. PMID:24428359
Cooper, Jason K; Benjamin, Ilan
Ionization and Excitation in Non-Polar Organic Liquids.
ERIC Educational Resources Information Center
Reviews recent advances in radiation chemistry concerning the effect of high-energy radiation on organic liquids. Discusses the general nature of excited and ionized states, pathways for decay, the effect of environmental perturbation, the behavior of an electron in a nonpolar liquid, and comparison of photochemical and radiation chemical effects.�
Lipsky, Sanford
Elementary excitation and energy landscape in simple liquids
NASA Astrophysics Data System (ADS)
The nature of excitations in liquids has been a subject of debate for a long time. In liquids, phonons are extremely short-lived and marginalized. Instead, recent research results indicate that local topological or configurational excitations (anankeons) are the elementary excitations in high temperature metallic liquids. Local topological excitations are those which locally alter the atomic connectivity network by cutting or forming atomic bonds, and are directly tied to the atomistic origin of viscosity in the liquid. The local potential energy landscape (PEL) of anankeons represents the probability weighted projection of the global PEL to a single atom. The original PEL is an insightful concept, but is highly multi-dimensional and difficult to characterize or even to visualize. A description in terms of the local PEL for anankeons appears to offer a simpler and more effective approach toward this complex problem. At the base of these advances, is the recognition that atomic discreteness and the topology of atomic connectivity are the most crucial features of the structure in liquids, which current nonlinear continuum theories cannot fully capture. These discoveries could open the way to the explanation of various complex phenomena in liquids, such as atomic transport, fragility, and the glass transition, in terms of these excitations.
Egami, T.
Effective interactions and elementary excitations in quantum liquids
The effective interactions which provide a wavevector and frequency dependent restoring force for collective modes in quantum liquids are derived for the helium liquids by means of physical arguments and sum rule and continuity considerations. A simple model is used to take into account mode-mode coupling between collective and multiparticle excitations, and the results for the zero-temperature liquid /sup 4/He phonon-maxon-roton spectrum are shown to compare favorably with experiment and with microscopic calculation. The role played by spin-dependent backflow in liquid /sup 3/He is analyzed, and a physical interpretation of its variation with density and spin-polarization is presented. A progress report is given on recent work on effective interactions and elementary excitations in nuclear matter, with particular attention to features encountered in the latter system which have no counterparts in the helium liquids.
Pines, D.
Response of Differently Axially Excited Viscous Liquid Bridges in Zero-Gravity.
National Technical Information Service (NTIS)
A cylindrical liquid column of incompressible and viscous liquid is subjected to different axial excitation: one-sided, counter-directional and double-sided unequal excitations. The response of the free liquid surface relating to the velocity and pressure...
H. F. Bauer
The liquid to vapor phase transition in excited nuclei
For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid-vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197 Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.
Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.J.; Beaulieu, L.; Breuer, H.; Korteling, R.G.; Kwiatkowski, K.; Lefort, T.; Pienkowski, L.; Ruangma, A.; Viola, V.E.; Yennello, S.J.
A quantum liquid with deconfined fractional excitations in three dimensions
NASA Astrophysics Data System (ADS)
Excitations which carry ``fractional'' quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However the existence of fractional excitations in three dimensions remains highly controversial. Here we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model --- the quantum dimer model on a diamond lattice [1]. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1) dimensional quantum electrodynamics [2,3]. [4pt] [1] O. Sikora et al. arXiv:0901.1057v3 --- to appear in Phys. Rev. Lett. [0pt] [2] R. Moessner and S.L. Sondhi, Phys. Rev. B 68, 184512 (2003).[0pt] [3] D.L. Bergman et al. Phys. Rev. B 73, 134402 (2006).
Shannon, Nic; Sikora, Olga; Pollmann, Frank; Penc, Karlo; Fulde, Peter
Conformal field theory in the Tomonaga Luttinger model with the 1\\/rbeta long-range interaction
We attempt to construct U(1) conformal field theory (CFT) in the Tomonaga-Luttinger (TL) liquid with the 1\\/rbeta long-range interaction (LRI). Treating the long-range forward scattering as a perturbation and applying CFT to it, we derive finite size scalings which depend on the power of the LRI. The obtained finite size scalings give nontrivial behaviours when beta is odd and is
Hitoshi Inoue; Kiyohide Nomura
Conformal field theory approach to gapless 1D fermion systems and application to the edge excitations of ?=1\\/(2 p +1) quantum Hall sequences
An effective conformal field theory (CFT) describing the low-energy excitations of a gas of spinless interacting fermions\\u000a on a circle in the gapless regime (Luttinger liquid) is investigated. Functional techniques and modular-transformation properties\\u000a are used to compute all correlation functions for a finite size and temperature. Forward-scattering disorder is treated exactly.\\u000a Laughlin experiments on charge transport in a quantum Hall
P. Degiovanni; R. M�lin; C. Chaubet
Acoustic excitation of liquid fuel droplets and coaxial jets
NASA Astrophysics Data System (ADS)
This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase of the acoustic field generated within the chamber on the dark core length and the inner jet spreading angles is presented and the stability of coaxial flows in the current flow regime is discussed with respect to evidence for convective and absolute jet instabilities under different operating conditions.
Rodriguez, Juan Ignacio
Liquid hydrogen suction dip and slosh wave excitation during draining under normal and reduced gravity environments
NASA Technical Reports Server (NTRS)
The paper discusses the dynamical behavior of vapor ingestion, liquid residual at the incipience of suction dip, slosh wave excitation under normal and reduced gravity and different flow rates during liquid hydrogen draining. Liquid residuals at the incipience of suction dip increase as the values of gravity decrease. Also liquid residuals increase with the draining flow rates. Lower ratio of Bond number and Weber number are unable to excite slosh waves. Lower flow rates and higher gravity excites waves with lower frequencies and higher wave amplitude slosh waves.
Hung, R. J.; Shyu, K. L.
A numerical study of liquid sloshing in a two-dimensional tank under external excitations
NASA Astrophysics Data System (ADS)
In this research, liquid sloshing behavior in a 2-D rectangular tank was simulated using ANSYS-FLUENT software subject to single or multiple-coupled external excitations (such as sway coupled with roll, and sway and roll coupled with heave). The volume of fluid (VOF) method was used to track the free surface of sloshing. External excitation was imposed through the motion of the tank by using the dynamic mesh technique. The study shows that if the tank is subjected to multiple coupled excitations and resonant excitation frequencies, liquid sloshing will become violent and sloshing loads, including impact on the top wall, will be intensified.
Hou, Ling; Li, Fangcheng; Wu, Chunliang
Magnetoelastic Excitations in the Pyrochlore Spin Liquid Tb2Ti2O7
NASA Astrophysics Data System (ADS)
At low temperatures, Tb2Ti2O7 enters a spin liquid state, despite expectations of magnetic order and/or a structural distortion. Using neutron scattering, we have discovered that in this spin liquid state an excited crystal field level is coupled to a transverse acoustic phonon, forming a hybrid excitation. Magnetic and phononlike branches with identical dispersion relations can be identified, and the hybridization vanishes in the paramagnetic state. We suggest that Tb2Ti2O7 is aptly named a "magnetoelastic spin liquid" and that the hybridization of the excitations suppresses both magnetic ordering and the structural distortion. The spin liquid phase of Tb2Ti2O7 can now be regarded as a Coulomb phase with propagating bosonic spin excitations.
Fennell, T.; Kenzelmann, M.; Roessli, B.; Mutka, H.; Ollivier, J.; Ruminy, M.; Stuhr, U.; Zaharko, O.; Bovo, L.; Cervellino, A.; Haas, M. K.; Cava, R. J.
Excitation of Meridional Flow by Differential Rotation in Earth's Liquid Core
NASA Astrophysics Data System (ADS)
The authors investigate the excitation of meridional flow by the differential rotation of the Earth's liquid core. The excitation mechanism is based on the hypothesis about the primary role of the differential rotation of the inner core and mantle. For cylindrical and spherical liquid layers confined between two rotating axially symmetric shells, the conditions for the azimuth flow instability which creates a meridional component were obtained. Methods were proposed for the solution of nonlinear equations describing steady flows at large Reynold numbers.
Loginov, A. A.; Samoilenko, Yu. I.; Tkachenko, V. A.
Liquid hydrogen slosh waves excited by constant reverse gravity acceleration of geyser initiation
NASA Technical Reports Server (NTRS)
The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank before main engine restart poses a microgravity fluid behavior problem. Resettlement or reorientation of liquid propellant can be accomplished by providing the optimal acceleration to the spacecraft such that the propellant is reoriented over the tank outlet. In this study slosh wave excitation induced by the resettling flowfield during the course of liquid reorientation with the initiation of geyser for liquid-filled levels of 30, 50, 65, 70, and 80 percent have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitations will affect the fluid stress distribution exerted on the container wall and shift the fluid mass distribution inside the container, which imposes the time-dependent variations in the moment of inertia of the container. This information is important for the spacecraft control during the course of liquid reorientation.
Hung, R. J.; Shyu, K. L.; Lee, C. C.
Excitation of electrohydrodynamic surface waves on a conducting liquid jet employing AC field
A method of exciting waves on the surface of a conducting liquid jet by means of time varying electric field is presented. The prime objective of employing such a technique is to produce, electrostatically, a monodisperse spray of highly conducting liquid, in a controlled manner. This method relies on the use of an AC field in a certain frequency range
Z. Huneiti; W. Machowski; W. Balachandran
Acoustic excitation of liquid fuel droplets and coaxial jets
This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the
Juan Ignacio Rodriguez
Effective interactions, elementary excitations, and transport in the helium liquids
Polarization potentials, the self-consistent fields which describe the primary consequences of the strong atom-atom interaction in the helium liquids, are developed for liquid /sup 4/He and /sup 3/He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero point motion, and the Pauli principle) which determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon-maxon-roton spectra of /sup 4/He and /sup 3/He-/sup 4/He mixtures, the phonon-maxon spectrum of normal and spin-polarized /sup 3/He, and the transport properties of superfluid /sup 4/He and of normal and spin-polarized /sup 3/He.
Pines, D.
Sloshing response of nonuniform density liquid in a laterally excited tank
A study on the sloshing response of nonuniform density liquid in a tank undergoing lateral base excitations is presented. The system considered is a circular cylindrical tank containing a liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous function. In the analysis, the liquid field is divided into n layers. The thicknesses of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and its value is assigned to be the value of the original liquid density at the mid-height of that layer. The problem is solved by the transfer matrix technique. The effect of the nonuniform liquid density on the sloshing response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response functions examined include the sloshing frequencies, surface wave height, and the associated convective hydrodynamic pressure. The results are presented in tabular and graphical forms. It is found that the natural frequencies of the sloshing motion for nonuniform density liquid are lower than those of the uniform density liquid of the same total depth contained in an identical tank. Also, it is shown that for nonuniform density liquid, the maximum sloshing wave height may increase significantly and the magnitude of the convective hydrodynamic pressure may be quite different compared with that of a uniform liquid contained in an identical tank.
Tang, Y. [Argonne National Lab., IL (United States). Reactor Engineering Division
The Kohn-Luttinger superconductivity in idealized doped graphene
NASA Astrophysics Data System (ADS)
Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter.
Kagan, M. Yu.; Val?kov, V. V.; Mitskan, V. A.; Korovushkin, M. M.
Conformal field theory in Tomonaga-Luttinger model with $1\\/r^\\\\beta$ type long-range interactions
The validity of the CFT in the Tomonaga-Luttinger liquid with the $1\\/r^\\\\beta$\\u000atype long-range interactions is discussed. The arguments by CFT for long-range\\u000aforward scatterings predict the finite size corrections which depend on the\\u000apower of the long-range interactions. Especially from finite size corrections\\u000ain the ground state, we find the effective central charge deviates from $c=1$.\\u000aThese conformal arguments
Hitoshi Inoue
Excitations in a perfect magnetized quantum spin ladder
NASA Astrophysics Data System (ADS)
The strong-leg S=1/2 Heisenberg spin ladder system C7(D10N)2CuBr4 is investigated in applied magnetic fields using inelastic neutron scattering anf DMRG calculations. The spectrum in the high-field Tomonaga-Luttinger spin liquid phase is found to be qualitatively different from that in the low-field spin gap phase. In the former, numerous spectral featrures, including incommensurate excitations and multi-spinon continua are identified. In contrast, the latter is dominated by long-lived magnon excitations and two-magnon bound states [1]. An unprecedented quantitive agreement between experiment and numerical claculations is achieved.[4pt] [1] D. Schmidiger, P. Bouillot, S. Muhlbauer, S. Gvasaliya, C. Kollath, T. Giamarchi, A. Zheludev, Phys. Rev. Lett. 108, 167201 (2012).
Zheludev, Andrey; Schmidiger, David; Muehlbauer, Sebastian; Severian, Gvasaliya; Bouillot, Pierre; Kollath, Corinna; Giamarchi, Thierry; Guidi, Tatiana; Bewley, Robert; Ehlers, Georg
A Study of NOx Reduction by Acoustic Excitation in a Liquid Fueled Burner
This paper presents the results of a controlled acoustic excitation of a liquid fueled non-premixed flame as a means of nitric oxide reduction. The experimental burner is a domestic hot-water heater provided by Viessmann. An actuator is located on the air duct and comprises two perforated plates. By changing the speed of rotation of the rotor it is possible to
Topological excitations and the dynamic structure factor of spin liquids on the kagome lattice
NASA Astrophysics Data System (ADS)
Recent neutron scattering experiments on the spin-1/2 kagome lattice antiferromagnet ZnCu3(OH)6Cl2 (Herbertsmithite) provide the first evidence of fractionalized excitations in a quantum spin liquid state in two spatial dimensions. In contrast to existing theoretical models of both gapped and gapless spin liquids, which give rise to sharp dispersing features in the dynamic structure factor, the measured dynamic structure factor reveals an excitation continuum that is remarkably flat as a function of frequency. Here we show that many experimentally observed features can be explained by the presence of topological vison excitations in a Z2 spin liquid. These visons form flat bands on the kagome lattice, and thus act as a momentum sink for spin-carrying excitations that are probed by neutron scattering. We compute the dynamic structure factor for two different Z2 spin liquids and find that our results for one of them are in qualitative agreement with the neutron scattering experiments above a very low energy cutoff, below which the structure factor is probably dominated by impurities.
Punk, Matthias; Chowdhury, Debanjan; Sachdev, Subir
Excitations from a chiral magnetized state of a frustrated quantum spin liquid
We study excitations in weakly interacting pairs of quantum spin ladders coupled through geometrically frustrated bonds. The ground state is a disordered spin liquid, at high fields replaced by an ordered chiral helimagnetic phase. The spectra observed by high-field inelastic neutron scattering experiments on the prototype compound Sul Cu2Cl4 are qualitatively different from those in the previously studied frustration-free spin liquids. Beyond the critical field Hc = 3.7 T, the soft mode that drives the quantum phase transition spawns two separate excitations: a gapless Goldstone mode and a massive magnon. Additional massive quasiparticles are clearly visible below Hc, but are destroyed in the ordered phase. In their place one observes a sharply bound excitation continuum.
Garlea, Vasile O [ORNL; Zheludev, Andrey I [ORNL; Tsvelik, A. [Brookhaven National Laboratory (BNL); Regnault, L.-P. [CEA, Grenoble, France; Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Kiefer, K. [Hahn-Meitner Institut, Berlin, Germany; Roessli, Bertrand [Swiss Spallation Neutron Source SINQ
Ward Identities and Chiral Anomaly in the Luttinger Liquid
Systems of interacting non-relativistic fermions in d =1, as well as spin chains or interacting two dimensional Ising models, verify an hidden approximate Gauge invariance which can be used to derive suitable Ward identities. Despite the presence of corrections and anomalies, such Ward identities can be implemented in a Renormalization Group approach and used to exploit nontrivial cancellations which allow
Giuseppe Benfatto; Vieri Mastropietro
Wentzel-Bardeen singularity in coupled Luttinger liquids: Transport properties
The recent progress on 1 D interacting electrons systems and their applications to study the transport properties of quasi one dimensional wires is reviewed. We focus on strongly correlated elections coupled to low energy acoustic phonons in one dimension. The exponents of various response functions are calculated, and their striking sensitivity to the Wentzel-Bardeen singularity is discussed. For the Hubbard model coupled to phonons the equivalent of a phase diagram is established. By increasing the filling factor towards half filling the WB singularity is approached. This in turn suppresses antiferromagnetic fluctuations and drives the system towards the superconducting regime, via a new intermediate (metallic) phase. The implications of this phenomenon on the transport properties of an ideal wire as well as the properties of a wire with weak or strong scattering are analyzed in a perturbative renormalization group calculation. This allows to recover the three regimes predicted from the divergence criteria of the response functions.
Martin, T.
1\\/f noise and Luttinger liquid phenomena in carbon nanotubes
Carbon nanotubes (CNTs) provide an ideal medium for testing the behavior of one-dimensional electron systems and are promising candidates for electronic applications such as sensors or field-effect transistors. This thesis describes the use of low frequency resistance fluctuations to measure both the properties of the one-dimensional electron system in CNTs, and the sensitivity of CNT devices to their environment. Low
David Andrew Tobias
Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian
We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378 (2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the 'Zitterbewegung' of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.
Jiang, Z.F.; /Beijing, Inst. Phys.; Li, R.D.; /Peking U.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.; Liu1, W.M.; /Beijing, Inst. Phys.
Electron kinetics in liquid water excited by a femtosecond VUV laser pulse
NASA Astrophysics Data System (ADS)
We model numerically the interaction of an ultrashort VUV laser pulse (FWHM = 10 fs, photon energy of 100 eV) with liquid water. The incident laser photons interact with water by ionizing water molecules and creating free electrons. These excited electrons are elastically scattered by water molecules and are able to produce secondary electrons via ionization. To track each free electron and its collisions event by event, we use the Monte Carlo method similar to (N. Medvedev and B. Rethfeld, Transient dynamics of the electronic subsystem of semiconductors irradiated with an ultrashort vacuum ultraviolet laser pulse, New Journal of Physics, Vol. 12, p. 073037 (2010)). This approach allows us to describe the transient non-equilibrium behaviour of excited electrons on femtosecond time scales. We present transient electron energy distributions and a time resolved energy transfer, i.e.: the changing kinetic energy of excited electrons, the increase of the energy of holes, and excitation of water molecules via elastic collisions. We compare results obtained with different models for the energy levels in liquid water: either assuming dense water vapour or an amorphous semiconductor with a band gap.
Huthmacher, Klaus; Medvedev, Nikita; Rethfeld, B�rbel
Liquid laser cavities and waveguides. III. Radiation coupling-out and fluorescence under uniform excitation. 'Evapolators'
An investigation was made of laser radiation coupling-out from totally reflecting closed liquid cavities by local frustration of total internal reflection with the aid of internal water spheres and external contact with a substrate or a prism. A rotating drop of ethanol containing rhodamine B in an envelope of liquid C{sub 8}F{sub 18} generated laser radiation with a divergence of several angular degrees and an efficiency up to 5% relative to the excitation energy. A transparent drop of ethanol with rhodamine B, suspended in air, and subjected to uniform pumping was used to determine the depth of the zone in which lasing took place in a liquid cavity. An increase in the integral (during the pump time) fluorescence energy from a selected internal part of this drop, which did not participate in lasing, on increase in the excitation flux was in agreement with the expectations and it began to fall at high pump intensities. Characteristics of oscillations in immiscible liquids which evaporated in an evaporator - oscillator ('evapolator') were discussed. (control of laser radiation parameters)
Belonogov, A Yu; Startsev, Aleksandr V; Stoilov, Yurii Yu; Sung-Joo, Cho [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source: Assessment of plasma characteristics
NASA Astrophysics Data System (ADS)
The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as a secondary excitation source with a parametric evaluation regarding carrier gas flow rate, applied current, and electrode distance. With this parametric evaluation, plasma optical emission was monitored in order to obtain a fundamental understanding with regards to rotational temperature (Trot), excitation temperature (Texc), electron number density (ne), and plasma robustness. Incentive for these studies is not only for a greater overall fundamental knowledge of the APGD, but also in instrumenting a secondary excitation/ionization source following laser ablation (LA). Rotational temperatures were determined through experimentally fitting of the N2 and OH molecular emission bands while atomic excitation temperatures were calculated using a Boltzmann distribution of He and Mg atomic lines. The rotational and excitation temperatures were determined to be ~ 1000 K and ~ 2700 K respectively. Electron number density was calculated to be on the order of ~ 3 � 1015 cm- 3 utilizing Stark broadening effects of the H? line of the Balmer series and a He I transition. In addition, those diagnostics were performed introducing magnesium (by solution feed and laser ablation) into the plasma in order to determine any perturbation under heavy matrix sampling. The so-called plasma robustness factor, derived by monitoring Mg II/Mg I emission ratios, is also employed as a reflection of potential perturbations in microplasma energetics across the various operation conditions and sample loadings. While truly a miniaturized source (< 1 mm3 volume), the LS-APGD is shown to be quite robust with plasma characteristics and temperatures being unaffected upon introduction of metal species, whether by liquid or laser ablation sample introduction.
Manard, Benjamin T.; Gonzalez, Jhanis J.; Sarkar, Arnab; Dong, Meirong; Chirinos, Jose; Mao, Xianglei; Russo, Richard E.; Marcus, R. Kenneth
Biological membrane modeling with a liquid/liquid interface. Probing mobility and environment with total internal reflection excited fluorescence.
Total internal reflection of exciting light, in combination with fluorescence intensity and polarization measurements, was used to selectively study fluorescent compounds adsorbed to the interface region between two immiscible liquids. A fluorometer was constructed which provided excitation at variable angles of incidence and allowed sensitive detection of polarized fluorescence emitted from the interface. The compound 4,4'-bis-1-phenylamino-8-naphthalenesulfonate (bis-ANS) was examined at a decalin/water interface and was found to possess remarkable affinity for the interface region with the bulk of the adsorbed molecule residing in the decalin phase. The adsorbed fluorophore displayed an apparent hindered rotation in the plane of the interface with a rotational diffusion coefficient 3- to 12-fold lower than that expected for bis-ANS in solution. While other dyes examined were not found to be significantly surface active, the addition of cationic surfactant sufficed to induce adsorption of the anionic fluorophore 1-aminonaphthalene-3,6,8-trisulfonic acid. This fluoropore was found to reside in an aqueous environment when bound to the interface, and it also exhibited hindered rotation in the plane of the interface. As the concentrations of the dyes were increased, both adsorbed dyes exhibited polarization reductions consistent with excitation energy transfer. Adsorption of bis-ANS was reversed by addition of bovine serum albumin. The membrane protein cytochrome b5 was found not to bind at the decalin/water interface, indicating that interaction with lipid is required for its adherence to biological membranes.
Morrison, L E; Weber, G
Optical near-field excitation using liquid crystals on nanostructured photoreactive molecular thin films
NASA Astrophysics Data System (ADS)
Optical near-field excitations were investigated on the basis of molecular alignment control of liquid crystals (LCs) on an optically rewritable nanostructure of photoreactive molecular thin films. Twisted nematic (TN) cells of LC molecules were constructed utilizing ITO substrates with 260 nm gratings of an azobenzene molecular thin film, fabricated using standing evanescent waves. The polarization changes of light transmitted through the TN cells, which were due to the alignment changes of LC molecules locally rubbed by the azobenzene nanogratings, were observed. Furthermore, we demonstrated local plasmon excitation of Au nanowires deposited on the azobenzene nanogratings using oblique vacuum evaporation, a phenomenon that produced strong anti-optical absorption spectra. The modulation of the local plasmon resonance in metallic nanowires decorated with LC molecules was confirmed.
Ohdaira, Yasuo; Shinbo, Kazunari; Baba, Akira; Kato, Keizo; Kaneko, Futao
Products of the triplet excited state produced in the radiolysis of liquid benzene.
The radiation chemical yields of the products derived from the triplet excited state produced in the radiolysis of liquid benzene with gamma-rays, 10 MeV 4He ions, and 10 MeV 12C ions have been determined. Iodine scavenging techniques have been used to examine the formation and role of radicals, especially the H atom and phenyl radical. For all irradiation types examined here, the increase in hydrogen iodide yields with increasing iodine concentration matches the increase in iodobenzene yields. This agreement suggests that the benzene triplet excited state is the common precursor for the H atom and the phenyl radical. Pulse radiolysis studies in liquid benzene have determined the rate coefficients for the reactions of phenyl radicals with iodine and with the solvent benzene to be 9.3 x 10(9) M(-1) s(-1) and 3.1 x 10(5) M(-1) s(-1), respectively. Direct measurements of polymer formation, which refers to trimers (C18) and higher order compounds (>C18), in liquid benzene radiolysis using gamma-rays, 4He ions, and 12C ions at relatively high doses have been performed using gel permeation chromatography. The yields of trimers increase from gamma-rays to 12C ions due to the increased importance of intratrack radical-radical reactions that can be scavenged by the radical scavenging reactions of iodine. On the other hand, the >C18 product yields decrease from gamma-rays to 12C ions. The structure of the polymer consists of a partly saturated ring as determined by infrared and gas chromatography/mass spectrometry studies. A schematic representation for the radiolytic decomposition of the benzene triplet excited state is presented. PMID:16539438
Enomoto, Kazuyuki; Laverne, Jay A; Pimblott, Simon M
An unique method of determining the excitation energy migration coefficient in organic liquid scintillators
An experimental method is described to determine the excitation energy migration coefficient ? in an organic liquid scintillator\\u000a by measuring the energy transfer rate parameterk\\u000a 3 and the quenching rate parameterk\\u000a 7b\\u000a as a function of temperature in the range of 20�C�70�C. In this experiment we have used toluene as donor, ethyl-1-n-butyl-2-methyl-5-hydroxyindole-3-carboxylate (EBMHC) as acceptor and bromobenzene as quencher. The
S M Hanagodimath; G C Chikkur; G S Gadaginmath
Photodissociation of ICN in polar solvents: Evidence for long lived rotational excitation in room temperature liquids
NASA Astrophysics Data System (ADS)
Ultrafast polarized pump-probe spectroscopy has been used to study the ICN A~ band photodissociation dynamics in several molecular liquids (water, ethanol, methanol, and chloroform). By exciting at 224 and 255 nm and probing at 385 nm near the gas phase CN B<--X transition, the population and vector correlations in the resulting products have been followed with ~150 fs time resolution. The exhaustive gas-phase reaction dynamics charted for this system indicate that a substantial torque is imparted to the CN fragment in the ground state I dissociation channel while the CN is rotationally cold in the I* channel. The fate of the highly rotationally excited fragment in a liquid environment is explored in the present study. The transient pump-probe anisotropy in ethanol and methanol shows two time scales for decay, ~400 fs and 3-7 ps depending on excitation energy; the two time scales are assigned to the two product channels. The subpicosecond time scale is characteristic of rotational diffusion of thermalized CN while the longer several picosecond time scale suggests the rotationally hot CN rotate nearly freely for several picoseconds in the plane defined by the initial dissociative event. The rotational behavior of a diatomic fragment is considered between the free rotor and small-angle rotational diffusion limits. The CN photoproduct population dynamics are quite varied in the different solvents. In alcohols and chloroform, CN undergoes abstraction reactions with the solvent while in water there is no abstraction. Caging and diffusive geminate recombination dynamics apparently vary markedly in the different solvents; these effects are compared to molecular dynamics results for this photodissociation system. A large isotope effect is observed between H2O and D2O solvents in the product recombination dynamics.
Moskun, Amy C.; Bradforth, Stephen E.
Experiments with bubbles containing electrons in excited states in liquid helium
NASA Astrophysics Data System (ADS)
When a free electron is injected into liquid helium, it forms a microscopic bubble essentially free of helium atoms, which is referred to as an electron bubble. It represents a fine example of a quantum-mechanical particle confined in a potential well. The electron bubble has been the subject of extensive experimental study and its main properties are well understood. However, most of the work in the past has been done with bubbles containing electrons in ground states. We expanded the field of study by investigating the effect of bubbles containing electrons in excited states on cavitation in the liquid. The cavitation of excited-state bubbles was observed for the first time and the magnitude of explosion pressure was in good agreement with theoretical predictions. We also investigated the effect of these bubbles on cavitation over a range of temperatures and pressures. The results depend in a complicated way on these parameters and are not completely understood. In a second series of experiments, we have studied the effect of light on the mobility of electron bubbles. The mobility of ions was measured by a time-of-flight technique over a range of temperatures and pressures and a number of interesting phenomena, such as the trapping of ions into quantized vortices in the liquid, were observed. We then investigated the interaction of light with trapped ions and obtained some quantitative results. We also made an attempt to observe the so called exotic ions which are charged objects with mobility higher then that of electron bubbles. We have also studied the nucleation of bubbles in bubble chambers and proposed a simple model for this process. The theoretical predictions of this model turned out to be in good agreement with experimental results.
Konstantinov, Denis
Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory.
The use of a piezoelectric element (acoustic excitation) to vibrate the base of microcantilevers is a popular method for dynamic atomic force microscopy. In air or vacuum, the base motion is so small (relative to tip motion) that it can be neglected. However, in liquid environments the base motion can be large and cannot be neglected. Yet it cannot be directly observed in most AFMs. Therefore, in liquids, quantitative force and energy dissipation spectroscopy with acoustic AFM relies on theoretical formulae and models to estimate the magnitude of the base motion. However, such formulae can be inaccurate due to several effects. For example, a significant component of the piezo excitation does not mechanically excite the cantilever but rather transmits acoustic waves through the surrounding liquid, which in turn indirectly excites the cantilever. Moreover, resonances of the piezo, chip and holder can obscure the true cantilever dynamics even in well-designed liquid cells. Although some groups have tried to overcome these limitations (either by theory modification or better design of piezos and liquid cells), it is generally accepted that acoustic excitation is unsuitable for quantitative force and dissipation spectroscopy in liquids. In this paper the authors present a careful study of the base motion and excitation forces and propose a method by which quantitative analysis is in fact possible, thus opening this popular method for quantitative force and dissipation spectroscopy using dynamic AFM in liquids. This method is validated by experiments in water on mica using a scanning laser Doppler vibrometer, which can measure the actual base motion. Finally, the method is demonstrated by using small-amplitude dynamic AFM to extract the force gradients and dissipation on solvation shells of octamethylcyclotetrasiloxane (OMCTS) molecules on mica. PMID:22071495
Kiracofe, Daniel; Raman, Arvind
Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory
NASA Astrophysics Data System (ADS)
The use of a piezoelectric element (acoustic excitation) to vibrate the base of microcantilevers is a popular method for dynamic atomic force microscopy. In air or vacuum, the base motion is so small (relative to tip motion) that it can be neglected. However, in liquid environments the base motion can be large and cannot be neglected. Yet it cannot be directly observed in most AFMs. Therefore, in liquids, quantitative force and energy dissipation spectroscopy with acoustic AFM relies on theoretical formulae and models to estimate the magnitude of the base motion. However, such formulae can be inaccurate due to several effects. For example, a significant component of the piezo excitation does not mechanically excite the cantilever but rather transmits acoustic waves through the surrounding liquid, which in turn indirectly excites the cantilever. Moreover, resonances of the piezo, chip and holder can obscure the true cantilever dynamics even in well-designed liquid cells. Although some groups have tried to overcome these limitations (either by theory modification or better design of piezos and liquid cells), it is generally accepted that acoustic excitation is unsuitable for quantitative force and dissipation spectroscopy in liquids. In this paper the authors present a careful study of the base motion and excitation forces and propose a method by which quantitative analysis is in fact possible, thus opening this popular method for quantitative force and dissipation spectroscopy using dynamic AFM in liquids. This method is validated by experiments in water on mica using a scanning laser Doppler vibrometer, which can measure the actual base motion. Finally, the method is demonstrated by using small-amplitude dynamic AFM to extract the force gradients and dissipation on solvation shells of octamethylcyclotetrasiloxane (OMCTS) molecules on mica.
Kiracofe, Daniel; Raman, Arvind
Linear quantum quench in the Heisenberg XXZ chain: Time-dependent Luttinger-model description of a lattice system
NASA Astrophysics Data System (ADS)
We study variable-rate linear quenches in the anisotropic Heisenberg (XXZ) chain, starting at the XX point. This is equivalent to switching on a nearest-neighbor interaction for hard-core bosons or an interaction quench for free fermions. The physical observables we investigate are the energy pumped into the system during the quench, the spin-flip correlation function, and the bipartite fluctuations of the z component of the spin in a box. We find excellent agreement between exact numerics (infinite system time-evolving block decimation) and analytical results from bosonization, as a function of the quench time, spatial coordinate, and interaction strength. This provides a stringent and much-needed test of Luttinger liquid theory in a nonequilibrium situation.
Pollmann, Frank; Haque, Masudul; D�ra, Bal�zs
Effect of applied ac electric field on surface plasmon excitations at metal/liquid-crystal interface
NASA Astrophysics Data System (ADS)
It is well known that surface plasmon polaritons (SPPs) can be excited by p-polarized laser beam incident upon high-index prism/metal/dielectric medium used in Kretschmann configuration. The SPPs' onset, evidenced by a loss in the intensity of totally reflected light at a certain angle greater than the critical angle for total reflection, is sensitive to the dielectric properties of the medium. In the case when the dielectric medium is liquid crystal (LC), its dielectric properties can be modified by applied electric fields. We have carried out a set of experiments on high-index prism/Au/LC used in the Kretschmann configuration. Specifically, we have measured a set of attenuated total reflection (ATR) data as functions of incident angle for p-polarized 632 nm laser beam and ac electric fields for liquid crystals. We present data on the effects of the applied ac electric fields on the nature of the reflectivity vs angle curves and discuss the relevance of our observations to the electric-field-induced changes in the dielectric properties of the liquid crystal.
Tiwari, Kunal; Sharma, Suresh
Electro-tunable laser action in a dye-doped nematic liquid crystal waveguide under holographic excitation
NASA Astrophysics Data System (ADS)
Optically pumped distributed feedback lasing has been demonstrated in a dye-doped nematic liquid crystal (NLC) waveguide by holographic excitation. The excitation was performed by two-beam interference using Lloyd mirror configuration. With an applied electric field, continuous tuning of the lasing wavelength was realized due to the change of the effective refractive index of the NLC core layer caused by the reorientation of NLC molecules.
Matsui, Tatsunosuke; Ozaki, Masanori; Yoshino, Katsumi
Compositional contrast of biological materials in liquids using the momentary excitation of higher eigenmodes in dynamic atomic force microscopy.
Atomic Force microscope (AFM) cantilevers commonly used for imaging soft biological samples in liquids experience a momentary excitation of the higher eigenmodes at each tap. This transient response is very sensitive to the local sample elasticity under gentle imaging conditions because the higher eigenmode time period is comparable to the tip-sample contact time. By mapping the momentary excitation response, we demonstrate a new scanning probe spectroscopy capable of resolving with high sensitivity the variations in the elasticity of soft biological materials in liquids. PMID:19257574
Xu, Xin; Melcher, John; Basak, Sudipta; Reifenberger, Ron; Raman, Arvind
Anisotropic breakdown of Fermi liquid quasiparticle excitations in overdoped La2-xSrxCuO4
NASA Astrophysics Data System (ADS)
High-temperature superconductivity emerges from an un-conventional metallic state. This has stimulated strong efforts to understand exactly how Fermi liquids breakdown and evolve into an un-conventional metal. A fundamental question is how Fermi liquid quasiparticle excitations break down in momentum space. Here we show, using angle-resolved photoemission spectroscopy, that the Fermi liquid quasiparticle excitations of the overdoped superconducting cuprate La1.77Sr0.23CuO4 is highly anisotropic in momentum space. The quasiparticle scattering and residue behave differently along the Fermi surface and hence the Kadowaki-Wood's relation is not obeyed. This kind of Fermi liquid breakdown may apply to a wide range of strongly correlated metal systems where spin fluctuations are present.
Chang, J.; M�nsson, M.; Pailh�s, S.; Claesson, T.; Lipscombe, O. J.; Hayden, S. M.; Patthey, L.; Tjernberg, O.; Mesot, J.
Ultrafast spectroscopy of electron transfer dynamics in liquids; excitation transfer studies of phase transitions
NASA Astrophysics Data System (ADS)
The transfer of an electron from a donor to an acceptor is the fundamental step in a wide range of chemical and biological processes. As a result, electron-transfer reactions have been the focus of numerous theoretical and experimental efforts aimed at understanding the kinetics and mechanism of the transfer event. Liquid solvents are an important medium for electron-transfer processes. The influences of the distance dependence, diffusion, the radial distribution function, and the hydrodynamic effect have been incorporated into the theory of electron transfer in solution, as well as into the theory of electron transfer between donors and acceptors in the head group regions of micelles. The development of new laser system with a pulse duration of tens of femtoseconds, with tunable wavelength allowed us to study these processes on a considerably shorter time scale than previous studies. This allowed us to observe not only the diffusion controlled but also the kinetics of electron transfer for donor/acceptor pairs that are in close proximity. In one set of experiments we have studied the kinetics of electron transfer in electron accepting molecule (rhodamine 3B) dissolved in electron donating solvent (N,N-dimethylaniline). The data for the forward electron transfer and geminate recombination are approximated by the statistical theory of the electron transfer. Optical anisotropy observed in the experiment demonstrates the orientation dependence of the electron transfer rate. In further experiments we investigated the electron transfer in non-hydrogen bonding liquids of increasing viscosity. The effective value of the donor/acceptor electronic coupling was found to decrease with viscosity. Electron transfer experiments were also carried out on the surface of micelles. The systems studied are the hole donor octadecyl-rhodamine B (ODRB) and the hole acceptor N,N-dimethyl-aniline (DMA) in micelles made of dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB). It was found that the effective coupling is reduced compared to donor/acceptor pairs dissolved in simple liquids. In the 2nd half of thesis we have addressed the question of the dynamics of phase transitions. We have demonstrated the ability to use the fluorescent excitation-transfer technique to study the demixing of liquids specifically, kinetics of demixing water and 2,6-dimethylpyridine. These two liquids possess a low critical temperature point, which allowed us to use a temperature jump from a laser pulse to initiate the process of phase separation. It was found that Coumarin480 laser dye and HPTS (8-Hydroxypyrene-1,3,6-trisulfonic acid) fluorescent dye have significantly different solubilities in the components of the mixture. These dyes undergo excitation transfer from Coumarin480 to HPTS in the uniform state, but not in the phase-separated state. A system with a temperature jump pump and an excitation transfer probe measured the time scale of the initial step of the phase separation.
Goun, Alexei A.
High efficiency laser photothermal excitation of microcantilever vibrations in air and liquids
NASA Astrophysics Data System (ADS)
Photothermal excitation is a promising means of actuating microscale structures. It is gaining increased interest for its capability to excite atomic force microscopy (AFM) microcantilevers with wide frequency bandwidth in liquid environments yielding clean resonance peaks without spurious resonances. These capabilities are particularly relevant for high speed and high resolution, quantitative AFM. However, photothermal efficiency is low, which means a large amount of laser power is required for a given mechanical response. The high laser power may cause local heating effects, or spill over the cantilever and damage sensitive samples. In this work, it is shown that by simply changing from a probe with a rectangular cross-section to one with a trapezoidal cross-section, the photothermal efficiency of an uncoated silicon cantilever can be increased by more than a order of magnitude, and the efficiency of a coated cantilever can be increased by a factor of 2. This effect is demonstrated experimentally and explained theoretically using thermomechanical analysis. Results are shown for both air and water, and for normal bending and torsional oscillations.
Kiracofe, Daniel; Kobayashi, Kei; Labuda, Aleksander; Raman, Arvind; Yamada, Hirofumi
High efficiency laser photothermal excitation of microcantilever vibrations in air and liquids.
Photothermal excitation is a promising means of actuating microscale structures. It is gaining increased interest for its capability to excite atomic force microscopy (AFM) microcantilevers with wide frequency bandwidth in liquid environments yielding clean resonance peaks without spurious resonances. These capabilities are particularly relevant for high speed and high resolution, quantitative AFM. However, photothermal efficiency is low, which means a large amount of laser power is required for a given mechanical response. The high laser power may cause local heating effects, or spill over the cantilever and damage sensitive samples. In this work, it is shown that by simply changing from a probe with a rectangular cross-section to one with a trapezoidal cross-section, the photothermal efficiency of an uncoated silicon cantilever can be increased by more than a order of magnitude, and the efficiency of a coated cantilever can be increased by a factor of 2. This effect is demonstrated experimentally and explained theoretically using thermomechanical analysis. Results are shown for both air and water, and for normal bending and torsional oscillations. PMID:21280832
Kiracofe, Daniel; Kobayashi, Kei; Labuda, Aleksander; Raman, Arvind; Yamada, Hirofumi
Non-linear seismic response of base-isolated liquid storage tanks to bi-directional excitation
Seismic response of the liquid storage tanks isolated by lead-rubber bearings is investigated for bi-directional earthquake excitation (i.e. two horizontal components). The biaxial force-deformation behaviour of the bearings is considered as bi-linear modelled by coupled non-linear differential equations. The continuous liquid mass of the tank is modelled as lumped masses known as convective mass, impulsive mass and rigid mass. The
M. K. Shrimali; R. S. Jangid
Liquid sloshing in partly-filled laterally-excited circular tanks equipped with baffles
NASA Astrophysics Data System (ADS)
Linear potential theory in conjunction with the conformal mapping technique are employed to develop rigorous mathematical models for two-dimensional transient sloshing in non-deformable baffled horizontal circular cylindrical vessels, filled with inviscid incompressible fluids to arbitrary depths, and subjected to arbitrary time-dependent lateral accelerations. Three common baffle configurations are considered, namely, a pair of free surface-touching horizontal side baffles, and a central surface-piercing or bottom-mounted vertical baffle of arbitrary extension. The first few normalized antisymmetric/symmetric sloshing frequencies of the partially-filled tanks are tabulated for selected baffle extension and fill depth ratios. Also, the effects of liquid fill depth or baffle length parameter on the impulsive, total and modal convective mass ratios are examined. A ramp-step function is used to replicate the lateral acceleration excitation encountered in an idealized turning maneuver. Durbin's numerical Laplace transform inversion scheme was applied to solve the resulting truncated linear sets of ordinary differential equations in the time-domain. The effects of excitation input time, fill level, and baffle configuration/extension on the force and moment amplification factors are illustrated through appropriate design charts. Furthermore, the transient hydrodynamic responses to a real seismic event are calculated and the effectiveness of baffle configuration/length on suppression of the induced destabilizing lateral forces are examined. Limiting cases are considered and rigorous verifications are made by comparison with the available data as well as with the numerical simulations performed by using a commercial CFD software package.
Hasheminejad, Seyyed M.; Mohammadi, M. M.; Jarrahi, Miad
Photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid
The authors present an optically based method combining photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid. The frequency spectrum of a silicon cantilever measured in water over frequencies ranging up to 10 MHz shows that the method allows us to excite and detect higher modes, from fundamental to fifth flexural, without enhancing spurious resonances. By reducing the tip oscillation amplitude using higher modes, the average tip-sample force gradient due to chemical bonds is effectively increased to achieve high-spatial-resolution imaging in liquid. The method's performance is demonstrated by atomic resolution imaging of a mica surface in water obtained using the second flexural mode with a small tip amplitude of 99 pm; individual atoms on the surface with small height differences of up to 60 pm are clearly resolved.
Nishida, Shuhei; Kobayashi, Dai; Sakurada, Takeo; Nakazawa, Tomonori; Hoshi, Yasuo; Kawakatsu, Hideki [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)
Excitation wavelength dependence of excited state intramolecular proton transfer reaction of 4'-N,N-diethylamino-3-hydroxyflavone in room temperature ionic liquids studied by optical Kerr gate fluorescence measurement.
Excited state intramolecular proton transfer reactions (ESIPT) of 4'-N,N-diethylamino-3-hydroxyflavone (DEAHF) in ionic liquids have been studied by steady-state and time-resolved fluorescence measurements at different excitation wavelengths. Steady-state measurements show the relative yield of the tautomeric form to the normal form of DEAHF decreases as excitation wavelength is increased from 380 to 450 nm. The decrease in yield is significant in ionic liquids that have cations with long alkyl chains. The extent of the decrease is correlated with the number of carbon atoms in the alkyl chains. Time-resolved fluorescence measurements using optical Kerr gate spectroscopy show that ESIPT rate has a strong excitation wavelength dependence. There is a large difference between the spectra at a 200 ps delay from different excitation wavelengths in each ionic liquid. The difference is pronounced in ionic liquids having a long alkyl chain. The equilibrium constant in the electronic excited state obtained at a 200 ps delay and the average reaction rate are also correlated with the alkyl chain length. Considering the results of the steady-state fluorescence and time-resolved measurements, the excitation wavelength dependence of ESIPT is explained by state selective excitation due to the difference of the solvation, and the number of alkyl chain carbon atoms is found to be a good indicator of the effect of inhomogeneity for this reaction. PMID:24088033
Suda, Kayo; Terazima, Masahide; Sato, Hirofumi; Kimura, Yoshifumi
An atmospheric air gas-liquid diffuse discharge excited by bipolar nanosecond pulse in quartz container used for water sterilization
NASA Astrophysics Data System (ADS)
In this Letter, we report that the air gas-liquid diffuse discharge plasma excited by bipolar nanosecond pulse in quartz container with different bottom structures at atmospheric pressure. Optical diagnostic measurements show that bountiful chemically and biologically active species, which are beneficial for effective sterilization in some areas, are produced. Such diffuse plasmas are then used to treat drinking water containing the common microorganisms (Candida albicans and Escherichia coli). It is found that these plasmas can sterilize the microorganisms efficiently.
Wang, Sen; Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Liu, Zhi-Jie; Tang, Kai; Song, Ying
Single-Mode Operation of Electrotunable Laser in a Dye-Doped Nematic Liquid-Crystal Waveguide under Holographic Excitation
NASA Astrophysics Data System (ADS)
Optically pumped distributed feedback (DFB) lasing has been demonstrated in a dye-doped nematic liquid-crystal (NLC) waveguide by holographic excitation. Utilizing NLC with a low refractive index, the single-mode operation of a laser action was realized. With an applied electric field, continuous tuning of the single-mode lasing wavelength was realized due to the change in the effective refractive index of the NLC core layer caused by the reorientation of NLC molecules.
Matsui, Tatsunosuke; Ozaki, Masanori; Yoshino, Katsumi
Evidence of scattering of bulk elementary excitations in isotopically pure liquid helium-II at low temperatures
NASA Astrophysics Data System (ADS)
This short report is concerned with experimental investigations of bulk elementary excitations (BEEs) in the isotopically pure liquid helium-II at low temperatures below 100 mK. The evidence of BEEs? scattering is introduced in this work. Two identical Au-heaters were used to generate BEEs. The first pulsed heater generates BEE beams to record them. The second heater serves to generate BEE beams in order to scatter the first beams, operating delay time between pulses of the heaters. Experimental signals were recorded by several bolometers situated both above and below the liquid surface: scattered BEEs are travelling in the liquid from the pulsed heater to the bolometer; scattered BEEs, reaching the liquid surface, evaporate 4He-atoms detected by two bolometers positioned in a vacuum; scattered signals are reflected from the liquid surface back to the liquid and are detected by the other bolometer situated in the liquid. It is manifested that the experimental results showed a dramatic decrease in peaks of recorded signals. Also, signal losses for different heater powers were calculated.
Zakharenko, A. A.
Lowering the excitation threshold of a random laser using the dynamic scattering states of an organosiloxane smectic A liquid crystal
NASA Astrophysics Data System (ADS)
Smectic A liquid crystals, based upon molecular structures that consist of combined siloxane and mesogenic moieties, exhibit strong multiple scattering of light with and without the presence of an electric field. This paper demonstrates that when one adds a laser dye to these compounds it is possible to observe random laser emission under optical excitation, and that the output can be varied depending upon the scattering state that is induced by the electric field. Results are presented to show that the excitation threshold of a dynamic scattering state, consisting of chaotic motion due to electro-hydrodynamic instabilities, exhibits lower lasing excitation thresholds than the scattering states that exist in the absence of an applied electric field. However, the lowest threshold is observed for a dynamic scattering state that does not have the largest scattering strength but which occurs when there is optimization of the combined light absorption and scattering properties.
Morris, Stephen M.; Gardiner, Damian J.; Qasim, Malik M.; Hands, Philip J. W.; Wilkinson, Timothy D.; Coles, Harry J.
Sloshing response of nonuniform density liquid in a laterally excited tank
A large number of high level waste (HLW) storage tanks at various facilities contain liquid with nonuniformity density. Exploratory studies show that the dynamic response of a tank containing two liquids is quite different from that of an identical tank containing only one liquid. To design and evaluate the HLW storage tanks it is necessary to understand the sloshing response of tanks that contain liquid with nonuniform density. The system considered is a circular cylindrical tank containing a liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous function. In the analysis, the liquid field is divided into n layers. The thicknesses of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and its value is assigned to be the value of the original liquid density at the mid-height of that layer. The problem is solved by the transfer matrix technique. The effect of the nonuniform liquid density on the sloshing response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response functions examined include the sloshing frequencies, surface wave height, and the associated convective hydrodynamic pressure. The results are presented in tabular and graphical forms. It is found that the natural frequencies of the sloshing motion for nonuniform density liquid are lower than those of the uniform density liquid of the same total depth contained in an identical tank. Also, it is shown that for nonuniform density liquid, the maximum sloshing wave height may increase significantly and the magnitude of the convective hydrodynamic pressure may be quite different compared with that of a uniform liquid contained in an identical tank.
Tang, Y.; Chang, Y.W.
The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.
Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)
Excitation energies and ionization potentials at high electric fields for molecules relevant for electrically insulating liquids
NASA Astrophysics Data System (ADS)
The electric-field dependence of the molecular ionization potential and excitation energies is investigated by density-functional theory calculations. It is demonstrated that the ionization potential has a strong field dependence and decreases with increasing field. The excitation energies depend weakly on the field and the number of available excited states decreases with increasing field since the ionization potential has a stronger field dependence. Above a specific field, different for each molecule, a two-state model is obtained consisting of the electronic ground state and the ionized state. Implications for streamer propagation and electrically insulating materials are discussed.
Davari, N.; A?strand, P.-O.; Ingebrigtsen, S.; Unge, M.
Minimal-excitation states for electron quantum optics using levitons
NASA Astrophysics Data System (ADS)
The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels; this allows the study of Abelian and non-Abelian quasiparticles in the time domain. Finally, the generation technique could be applied to cold atomic gases, leading to the possibility of atomic levitons.
Dubois, J.; Jullien, T.; Portier, F.; Roche, P.; Cavanna, A.; Jin, Y.; Wegscheider, W.; Roulleau, P.; Glattli, D. C.
Minimal-excitation states for electron quantum optics using levitons.
The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels; this allows the study of Abelian and non-Abelian quasiparticles in the time domain. Finally, the generation technique could be applied to cold atomic gases, leading to the possibility of atomic levitons. PMID:24153178
Dubois, J; Jullien, T; Portier, F; Roche, P; Cavanna, A; Jin, Y; Wegscheider, W; Roulleau, P; Glattli, D C
Dynamical mechanism for the intermolecular relaxation of the excited NH stretching vibration of a pyrrole molecule in liquid solution
NASA Astrophysics Data System (ADS)
Nonlinear Dynamics is used to explain the intermolecular relaxation of the NH strechinng vibration of pyrrole in liquid phase. We present first a two mode model, which implies a 3:1 anharmonic resonance between the NH Morse stretch of an excited pyrrole molecule and the ring mode (harmonic stretch) of a neighboring pyrrole molecule coupled by a hydrogen bond interaction. Next, the model has been extended to three modes, in order to better mimic the real phenomenon. We present here the population decay and vibrational relaxation time of the NH stretch for both models.
Mu�oz-Crego, C.; Santamar�a, J.
Edge excitations of paired fractional quantum Hall states
NASA Astrophysics Data System (ADS)
The Hilbert spaces of the edge excitations of several ``paired'' fractional quantum Hall states, namely, the Pfaffian, Haldane-Rezayi, and 331 states, are constructed and the states at each angular momentum level are enumerated. The method is based on finding all the zero-energy states for those Hamiltonians for which each of these known ground states is the exact, unique, zero-energy eigenstate of lowest angular momentum in the disk geometry. For each state, we find that, in addition to the usual bosonic charge-fluctuation excitations, there are fermionic edge excitations. The wave functions for each case have a similar form, related to Slater determinants, and the edge states satisfy a ``projection rule,'' that the parity of the number of fermions added to the edge equals the parity of the charge added. The edge states can be built out of quantum fields that describe the fermions, in addition to the usual scalar bosons (or Luttinger liquids) that describe the charge fluctuations. The fermionic fields in the Pfaffian and 331 cases are a noninteracting Majorana (i.e., real Dirac) and Dirac field, respectively. For the Haldane-Rezayi state, the field is an anticommuting scalar. For this system, we exhibit a chiral Lagrangian that has manifest SU(2) symmetry, but breaks Lorentz invariance, because of the breakdown of the spin-statistics connection implied by the scalar nature of the field and the positive-definite norm on the Hilbert space. Finally, we consider systems on a cylinder, where the fluid has two edges, and construct the sectors of zero-energy states, discuss the projection rules for combining states at the two edges, and calculate the partition function for each edge excitation system at finite temperature in the thermodynamic limit. The corresponding theory for the hierarchy and its generalizations is also given. It is pointed out that the conformal field theories for the edge states are examples of orbifold constructions. Two appendixes contain technical details.
Milovanovi?, M.; Read, N.
Investigation of liquid/solid interface waves with laser excitation and photoelastic effect detection
NASA Astrophysics Data System (ADS)
Theoretical and experimental investigations on transparent liquid (water)/solid (aluminum or steel) interface waves generated by laser pulse and detected with photoelastic effect are reported. When the detection beam of a laser interferometer is skimmed over the water/solid interface and conjoined with the interface wave propagated in water, an extra optical phase shift is produced. The output signal from the interferometer is proportional to the acoustic pressure in water. The characteristic equation of the liquid/solid interface wave is derived from elastic wave theory, and the transient response of acoustic pressure in water is simulated by means of inverse Laplace and Hankel transforms. The experimental results of acoustic velocity and wave form for all interface waves are in good agreement with theoretical predictions. They show that the optical detecting method based on photoelastic effect is very powerful for the research of liquid/solid interface waves.
Han, Qingbang; Qian, Menglu; Wang, Hao
Thermally excited capillary waves at vapor/liquid interfaces of water-alcohol mixtures
NASA Astrophysics Data System (ADS)
The density profiles of liquid/vapor interfaces of water-alcohol (methanol, ethanol and propanol) mixtures were studied by surface-sensitive synchrotron x-ray scattering techniques. X-ray reflectivity and diffuse scattering measurements, from the pure and mixed liquids, were analyzed in the framework of capillary wave theory to address the characteristic length scales of the intrinsic roughness and the shortest capillary wavelength (alternatively, the upper wavevector cutoff in capillary wave theory). Our results establish that the intrinsic roughness is dominated by average interatomic distances. The extracted effective upper wavevector cutoff indicates capillary wave theory breaks down at distances of the order of bulk correlation lengths.
Vaknin, David; Bu, Wei; Sung, Jaeho; Jeon, Yoonnam; Kim, Doseok
Energy spectrum of one-particle excitations in liquid dielectrics under high pressures and temperatures
The effect of pressure on the conductivity of molecular liquids (hydrogen, oxygen, and nitrogen) and alkali metals (cesium and rubidium) in the region of the experimentally observed dielectric-metal transition is investigated. It is shown that capture of free electrons by atoms or molecules (resulting in the formation of negative ions) is advantageous from the point of view of energy in
A. G. Khrapak; V. E. Fortov
Cholesteric liquid crystal laser in a dielectric mirror cavity upon band-edge excitation
Low threshold laser action of dye-doped cholesteric liquid crystals (CLCs) is demonstrated using an input circularly polarized light whose handedness is the same as the cholesteric helix of the sample at the high-energy band edge of the reflection band. The mechanism originates from the dramatic increase of the photon density of state at the band edges. We also demonstrate an
Yuko Matsuhisa; Yuhua Huang; Ying Zhou; Shin-Tson Wu; Yuuki Takao; Akihiko Fujii; Masanori Ozaki
Photoconductivity induced by single-proton excitation of aromatic molecules in liquid hydrocarbons
The spectral dependence of the photoconductivity of several aromatic solutes (anthracene, 1,2-benzanthracene, perylene, pyrene, azulene, ..cap alpha..-methylnaphthalene, and triphenylamine) in liquid hydrocarbon solvents (neopentane, 2,2,4-trimethylpentane(2,2,4-TMP), 2,2,4,4-tetramethylpentane (2,2,4,4-TMP), and n-pentane) are reported. In liquids which exhibit high thermal electron mobilities, relative maxima or shoulders are detected in the photoconductivity spectra. The corresponding transitions are thought to involve the formation of Rydberg states as precursors of separated charges. For anthracene and azulene, the transitions occur at approximately the same energy where Rydberg lines are observed in the gas phase. Quenching of the photoconductivity by perfluoromethylcyclohexane and by perfluoro-n-hexane supports this hypothesis.
Holroyd, R.A.; Preses, J.M.; Boettcher, E.H.; Schmidt, W.F.
Energy spectrum of one-particle excitations in liquid dielectrics under high pressures and temperatures
The effect of pressure on the conductivity of molecular liquids (hydrogen, oxygen, and nitrogen) and alkali metals (cesium\\u000a and rubidium) in the region of the experimentally observed dielectric-metal transition is investigated. It is shown that capture\\u000a of free electrons by atoms or molecules (resulting in the formation of negative ions) is advantageous from the point of view\\u000a of energy in
A. G. Khrapak; V. E. Fortov
Effect of the Bethe surface description on the electronic excitations induced by energetic proton beams in liquid water and DNA
NASA Astrophysics Data System (ADS)
The irradiation of biological systems by energetic ion beams has multiple applications in medical physics and space radiation health, such as hadrontherapy for cancer treatment or protection of astronauts against space radiation. Therefore, for a better control and understanding of the effects of radiation damage in living tissues, it is necessary to advance an accurate description of the energy loss from the ion beam to the target. In the present work we use the dielectric formalism to calculate the probability for an energetic proton to produce electronic excitations in two targets of high biological interest, namely, liquid water and DNA. Also, the mean energy of the electronic excitations in these targets is found as a function of the incident proton energy. The electronic response of the target, characterized by its energy-loss function (ELF), is described by several models that fit the available experimental optical data (at zero momentum transfer), but use different approaches to obtain the Bethe surface, that is, to extend the ELF to any energy and momentum transferred.
Abril, Isabel; Denton, Cristian D.; de Vera, Pablo; Kyriakou, Ioanna; Emfietzoglou, Dimitris; Garcia-Molina, Rafael
Optically excited XeF(asterisk) excimer laser in liquid argon
NASA Astrophysics Data System (ADS)
Stimulated emission on the B-X band of the XeF(asterisk) excimer molecule in the liquid phase at 404 nm was observed following transverse optical pumping at 351 nm. The energy of this emission was measured to be about 70 microjoules, and the pulse had a FWHM of about 5 nsec. The stimulated-emission spectrum showed considerable narrowing compared with the spontaneous-emission spectrum. The temporal behavior of the 404-nm pulse was investigated, and gain saturation of the lasing medium was observed.
Shahidi, M.; Jara, H.; Pummer, H.; Egger, H.; Rhodes, C. K.
Spiral and target patterns in bivalve nacre manifest a natural excitable medium from layer growth of a biological liquid crystal
Nacre is an exquisitely structured biocomposite of the calcium carbonate mineral aragonite with small amounts of proteins and the polysaccharide chitin. For many years, it has been the subject of research, not just because of its beauty, but also to discover how nature can produce such a superior product with excellent mechanical properties from such relatively weak raw materials. Four decades ago, Wada [Wada K (1966) Spiral growth of nacre. Nature 211:1427] proposed that the spiral patterns in nacre could be explained by using the theory Frank [Frank F (1949) The influence of dislocations on crystal growth. Discuss Faraday Soc 5:48�54] had put forward of the growth of crystals by means of screw dislocations. Frank's mechanism of crystal growth has been amply confirmed by experimental observations of screw dislocations in crystals, but it is a growth mechanism for a single crystal, with growth fronts of molecules. However, the growth fronts composed of many tablets of crystalline aragonite visible in micrographs of nacre are not a molecular-scale but a mesoscale phenomenon, so it has not been evident how the Frank mechanism might be of relevance. Here, we demonstrate that nacre growth is organized around a liquid-crystal core of chitin crystallites, a skeleton that the other components of nacre subsequently flesh out in a process of hierarchical self-assembly. We establish that spiral and target patterns can arise in a liquid crystal formed layer by layer through the Burton�Cabrera�Frank [Burton W, Cabrera N, Frank F (1951) The growth of crystals and the equilibrium structure of their surfaces. Philos Trans R Soc London Ser A 243:299�358] dynamics, and furthermore that this layer growth mechanism is an instance of an important class of physical systems termed excitable media. Artificial liquid crystals grown in this way may have many technological applications.
Cartwright, Julyan H. E.; Checa, Antonio G.; Escribano, Bruno; Sainz-Diaz, C. Ignacio
The Luttinger-Ward functional approach in the Eliashberg framework: a systematic derivation of scaling for thermodynamics near the quantum critical point.
Scaling expressions for the free energy are derived, using the Luttinger-Ward (LW) functional approach in the Eliashberg framework, for two different models of the quantum critical point (QCP). First, we consider the spin-density-wave model for which the effective theory is the Hertz-Moriya-Millis theory, describing the interaction between itinerant electrons and collective spin fluctuations. The dynamics of the latter are described using a dynamical exponent z depending on the nature of the transition. Second, we consider the Kondo breakdown model for QCPs, one possible scenario for heavy-fermion quantum transitions, for which the effective theory is given by a gauge theory in terms of conduction electrons, spinons for localized spins, holons for hybridization fluctuations, and gauge bosons for collective spin excitations. For both models, we construct the thermodynamic potential, in the whole phase diagram, including all kinds of self-energy corrections in a self-consistent way, at the one-loop level. We show how the Eliashberg framework emerges at this level and use the resulting Eliashberg equations to simplify the LW expression for the free energy. It is found that collective boson excitations play a central role. The scaling expression for the singular part of the free energy near the Kondo breakdown QCP is characterized by two length scales: one is the correlation length for hybridization fluctuations, and the other is that for gauge fluctuations, analogous to the penetration depth for superconductors. PMID:21427476
Benlagra, A; Kim, K-S; P�pin, C
Boson localization and excitations of liquid He4 confined in gelsil
NASA Astrophysics Data System (ADS)
We present neutron scattering measurements of the phonon-roton (P-R) modes of liquid He4 at saturated vapor pressure confined in 44� mean pore diameter gelsil in the wave vector range 0.4?Q?2.15�-1 . Layer modes, modes which propagate in the liquid layers adjacent to the porous media walls, were also observed at wave vectors in the roton region (Q?1.95�-1) but not at Q?1.7�-1 . The first goal is to document the filling dependence of the dynamic response and of the P-R mode energies and widths more systematically than has been done in the past. As the gelsil is filled with He4 , the P-R and layer modes are first observed at a fractional filling of f=76% at low temperature (T=0.4K) . At fillings f=76% , the P-R mode energies lie below the bulk superfluid He4 values in the wave vector range 0.4?Q?1.7�-1 , especially at Q?1.1�-1 , as observed in helium films. As filling is increased, the intensity in the P-R mode increases markedly and the P-R mode energies move toward bulk superfluid values taking bulk values at full filling. The second goal is to determine the temperature dependence of the intensity in the P-R modes in a media in which the superfluid-normal transition temperature Tc=1.92K is independently known and lies well below the bulk liquid value T?=2.17K . As temperature is increased, the intensity in the P-R and layer modes decreases. However, a well-defined P-R mode is observed at temperatures up to T?2.15K , above Tc=1.92K . Since well-defined modes exist because there is Bose-Einstein condensation (BEC), this suggests that there is BEC above Tc , probably localized. Localized BEC appears to exist up to T?T? .
Albergamo, Francesco; Bossy, Jacques; Pearce, Jonathan V.; Schober, Helmut; Glyde, Henry R.
Magnetic excitations in Kondo liquid: superconductivity and hidden magnetic quantum critical fluctuations
We report Knight shift experiments on the superconducting heavy electron material CeCoIn{sub 5} that allow one to track with some precision the behavior of the heavy electron Kondo liquid in the superconducting state with results in agreement with BCS theory. An analysis of the {sup 115}In nuclear quadrupole resonance (NQR) spin-lattice relaxation rate T{sub 1}{sup -1} measurements under pressure reveals the presence of 2d magnetic quantum critical fluctuations in the heavy electron component that are a promising candidate for the pairing mechanism in this material. Our results are consistent with an antiferromagnetic quantum critical point (QCP) located at slightly negative pressure in CeCoIn{sub 5} and provide additional evidence for significant similarities between the heavy electron materials and the high T{sub c} cuprates.
Yang, Yifeng [Los Alamos National Laboratory; Urbano, Ricardo [NHMFL, FL; Nicholas, Curro [UC DAVIS; Pines, David [UC DAVIS
Magnetic excitations in the kondo liquid: superconductivity and hidden magnetic quantum critical fluctuations.
We report Knight-shift experiments on the superconducting heavy-electron material CeCoIn5 that allow one to track with some precision the behavior of the heavy-electron Kondo liquid in the superconducting state with results in agreement with BCS theory. An analysis of the 115In nuclear quadrupole resonance spin-lattice relaxation rate T1(-1) measurements under pressure reveals the presence of 2d magnetic quantum critical fluctuations in the heavy-electron component that are a promising candidate for the pairing mechanism in this material. Our results are consistent with an antiferromagnetic quantum critical point located at slightly negative pressure in CeCoIn5 and provide additional evidence for significant similarities between the heavy-electron materials and the high-T(c) cuprates. PMID:20365948
Yang, Yi-Feng; Urbano, Ricardo; Curro, Nicholas J; Pines, David; Bauer, E D
Bose Einstein condensation: Its role in the excitations of liquid helium and in trapped Bose gases
NASA Astrophysics Data System (ADS)
The role of Bose-Einstein condensation (BEC) in determining the properties of Bose systems at ultracold temperatures is investigated. First, we present a model of the dynamic structure factor S(Q,o) of liquid 4He as observed in inelastic neutron scattering measurements beyond the roton (Q ? 2.0 A-1). We separate the dynamic susceptibility into chi = chiS + chi'R. chi S involves states in the condensate and chi' R states above the condensate only. We find that the weight of chiS scales with the condensate fraction n0(T) and vanishes at Tlambda. chi' R is broad and largely temperature independent and a low energy intensity broadening arises from the thermal broadening of the phonon-roton (p-r) modes. Secondly, we investigate ultracold Bose gases with repulsive and attractive interactions confined in a spherical harmonic trap over a broad range of densities using model potentials and variational Monte Carlo (VMC) at T = 0 K. In the case of repulsive interactions, the Bosons are represented by hard spheres (HS)s interacting by a HS potential. We change the densities of the Bosons by increasing the s-wave scattering length a. We find that the VMC total and VMC condensate density distributions are similar in shape, they are flat nearly at the higher densities. Further the Thomas-Fermi approximation becomes invalid and the condensate is substantially depleted at the higher densities. In the case of attractive interactions, we model the interactions by a hard core square well (HCSW). We change the densities of these systems by keeping the hard core diameter, a c, fixed and increasing the potential depth V 0 or by increasing both of them simultaneously while keeping a fixed. We find that a Bose gas with attractive interactions undergoes a first order phase transition from the gas to the liquid state at a value of N|a| ? 0.574 in agreement with the value predicted by Gross-Pitaevskii (GP) theory. The condensate depletion is mainly driven by the HC diameter in the presence of an attractive well. The scattering length is a useful representation of the HCSW at the low densities, but at the higher densities the HCSW is not represented well anymore by the scattering length.
Sakhel, Asaad R.
Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon
A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin's resonant energy transfer hopping mechanism.
Peterson, E.S.
Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon
A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin`s resonant energy transfer hopping mechanism.
Peterson, E.S.
Observation of particle hole asymmetry and phonon excitations in non-Fermi-liquid systems: A high-resolution photoemission study of ruthenates
NASA Astrophysics Data System (ADS)
We investigate the temperature evolution of the electronic states in the vicinity of the Fermi level of a non-Fermi-liquid (NFL) system, CaRuO3 using ultra high-resolution photoemission spectroscopy; isostructural SrRuO3 exhibiting Fermi-liquid behavior despite similar electron interaction parameters as that of CaRuO3, is used as a reference. High-energy resolution in this study helps to reveal particle-hole asymmetry in the excitation spectra of CaRuO3 in contrast to that in SrRuO3. In addition, we observe signature of phonon excitations in the photoemission spectra of CaRuO3 at finite temperatures while these are weak in SrRuO3.
Maiti, K.; Singh, R. S.; Medicherla, V. R. R.
Properties of bound, resonant, and regular continuum states of the excitation spectrum of symmetric liquid 4He films at T=0 K
Elementary excitations in rather thick symmetric films of liquid 4He at T=0 K are investigated. They are characterized by a momentum hq parallel to the surface and may be described by bound or continuum states, which are obtained by solving a Bogoliubov-type equation formulated within the framework of the paired-phonon analysis and the hypernetted-chain approximation. Films of coverages nc=0.3 and
Leszek Szybisz
Properties of bound, resonant, and regular continuum states of the excitation spectrum of symmetric liquid 4He films at T=0 K
NASA Astrophysics Data System (ADS)
Elementary excitations in rather thick symmetric films of liquid 4He at T=0 K are investigated. They are characterized by a momentum ?q parallel to the surface and may be described by bound or continuum states, which are obtained by solving a Bogoliubov-type equation formulated within the framework of the paired-phonon analysis and the hypernetted-chain approximation. Films of coverages nc=0.3 and 0.4 Å-2 confined by simple Gaussian potentials are studied. The excitation spectrum is numerically evaluated by discretizing the associated eigenvalue problem in a finite box. The evolution of the energy levels as a function of the box size is explored. Examples of the calculated energies and wave functions are displayed in a series of figures. Two differing sorts of continuum states may be distinguished. Depending on the behavior of their excitation energies as a function of the box size on the one hand, and the spatial distribution of their wave functions inside the film and in the asymptotic region far apart from the interface layer on the other, the continuum solutions can be separated into two classes of excitations: (a) the ``regular'' continuum states and (b) the ``resonant modes.'' The matrix elements of the particle-hole potential and the penetration factors of the most important states are examined. The lowest-lying branch of states is always bound and for q
excitations of the system. Our results support the occurrence of the repulsion between ``bulk'' and ripplon excitations proposed by Pitaevskii and Stringari. The strength of contributions originated from different normal modes to the liquid structure function is evaluated. While for very small values of momenta (q<=0.2 Å-1) the contribution of the lowest-lying normal mode is dominant, for momenta q>~qR the structure factor is determined by the contributions originated from the three lowest-lying even states. At q~=qR there is a dramatic transfer of strength from the bound continuation of the hardest ``resonant mode'' to the ripplon excitation. Experimental data of the inelastic structure factor S(q,??) may be satisfactorily interpreted on the basis of our calculation. On the other hand, it is shown that for 2.9<=q<=3.9 Å-1 the lowest-lying excitations become surface modes again.
Szybisz, Leszek
Dynamics of an elastic cylindrical shell with a gas�liquid medium subject to two-frequency vibrational excitation
The paper presents experimental results on nonlinear dynamic processes such as the deformation of the elastic wall of a cylindrical\\u000a shell filled with a fluid and the formation and clustering of gas bubbles, which interact under two-frequency excitation
V. D. Lakiza
The Kohn-Luttinger mechanism and phase diagram of the superconducting state in the Shubin-Vonsovsky model
Using the Shubin-Vonsovsky model in the weak-coupling regime W > U > V (W is the bandwidth, U is the Hubbard onsite repulsion, and V is the Coulomb interaction at neighboring sites) based on the Kohn-Luttinger mechanism, we determined the regions of the existence of the superconducting phases with the d{sub xy}, p, s, and d{sub x{sup 2}-y{sup 2}} symmetry types of the order parameter. It is shown that the effective interaction in the Cooper channel considerably depends not only on single-site but also on intersite Coulomb correlations. This is demonstrated by the example of the qualitative change and complication of the phase diagram of the superconducting state. The superconducting (SC) phase induction mechanism is determined taking into account polarization contributions in the second-order perturbation theory in the Coulomb interaction. The results obtained for the angular dependence of the superconducting gap in different channels are compared with angule-resolved photoemission spectroscopy (ARPES) results. The influence of long-range hops in the phase diagram and critical superconducting transition temperature in different channels is analyzed. The conditions for the appearance of the Kohn-Luttinger superconductivity with the d{sub x{sup 2}-y{sup 2}} symmetry and high critical temperatures T{sub c} {approx} 100 K near the half-filling are determined.
Kagan, M. Yu., E-mail: firstname.lastname@example.com [Russian Academy of Sciences, Kapitza Institute for Physical Problems (Russian Federation); Val'kov, V. V.; Mitskan, V. A.; Korovuskin, M. M. [Russian Academy of Sciences, Kirenskii Physics Institute, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Kirenskii Physics Institute, Siberian Branch (Russian Federation)
Yields of ions and excited states in nonpolar liquids exposed to x-rays of 1 to 30 kev energy.
National Technical Information Service (NTIS)
When x-rays from a synchrotron source are absorbed in a liquid, the x-ray energy (E(sub x)) is converted by the photoelectric effect into the kinetic energy of the electrons released. For hydrocarbons, absorption by the K-electrons of carbon dominates. Th...
Breakdown of the Fermi liquid due to long-range interactions
Fermions interacting via a long-range repulsive potential are considered in [ital D] spatial dimensions, where 1[lt][ital D][le]2. The standard screening picture is found to break down, i.e., the screened effective interaction cannot be treated as instantaneous. For a bare potential which behaves at long distances as [ital r][sup [minus](2[minus][ital D])] [as ln [ital r] in two dimensions (2[ital D])] and within the random-phase approximation, the retardation effects induce an infrared catastrophe that changes the Fermi liquid into a Luttinger liquid in which the occupation number in momentum space is continuous across the Fermi surface. In 2D, the quantum liquid which we investigate may be called a [ital Z]=0 Fermi liquid'' (where [ital Z] is the strength of the quasiparticle pole at the Fermi surface) since the electron propagator has an isolated pole with a constant residue that scales to zero as the size of the system increases to infinity. For 1[lt][ital D][lt]2, the quantum liquid resembles the 1D Luttinger liquid as the single-particle propagator exhibits a branch cut structure. Moreover, we present a ground-state wave function which reproduces the Luttinger-liquid exponent of the momentum distribution near the Fermi surface.
Bares, P.; Wen, X. (Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States))
Tunable laser action in a dye-doped nematic liquid-crystal waveguide under holographic excitation based on electric-field-induced TM guided-mode modulation
NASA Astrophysics Data System (ADS)
Electrically tunable laser action has been demonstrated in a dye-doped nematic liquid-crystal (NLC) waveguide by holographic excitation. The optical feedback was provided by the distributed feedback induced by two-beam interference by use of the Lloyd mirror configuration. Electrical tuning of the lasing wavelength was realized owing to the change of the effective refractive index of the NLC core layer caused by the reorientation of NLC molecules. On the basis of a waveguiding mode theory, numerical analysis of a TM guided mode in the presence of an applied electric field was performed, and field-induced tuning of the lasing wavelength was investigated in detail. Prospects for the realization of a single-mode operation and tuning of the lasing wavelength were also shown.
Matsui, Tatsunosuke; Ozaki, Masanori; Yoshino, Katsumi
Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air.
In this study, a bipolar nanosecond pulse with 20ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency. PMID:24845733
Wang, Sen; Wang, Wen-Chun; Yang, De-Zheng; Liu, Zhi-Jie; Zhang, Shuai
Resonance method of measuring shear viscoelastic properties of liquid media based on excitation of torsional oscillations in tubes
NASA Astrophysics Data System (ADS)
Possibilities of using torsional oscillations for measuring viscoelastic properties of liquids are discussed. The theory of torsional oscillations of an elastic tube filled with the media to be investigated possessing viscosity and shear elasticity is developed. It is shown that to determine a complex shear modulus it is sufficient to determine the resonance frequency and Q-factor of torsional oscillations. An experimental installation and the results of measurements of viscoelastic modulus of glycerin and oil of one oilfield within the temperature range from -10� to 60�C are given. The experimental installation allows measuring a viscoelastic modulus within the range of acoustic logging frequencies (10-20 kHz). The obtained results are compared with the results of rheometric measurements.
Esipov, I. B.; Zozulya, O. M.; Fokin, A. V.
Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation
NASA Astrophysics Data System (ADS)
In this study, the effectiveness of a tuned liquid column-gas damper, TLCGD, on the suppression of seismicinduced vibrations of steel jacket platforms is evaluated. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. The objective here is to find the optimum geometric parameters, namely orientation and configuration of vertical columns, length ratio, and area ratio of the TLCGD, considering nonlinear damping of the TLCGD and water-structure interaction between the jacket platform and sea water. The effects of different characteristics of ground motion such as PGA and frequency content on the optimum geometry are also investigated and it is observed that these features have some influence on the optimum area ratio. Finally it is observed that pulse arrangement of ground acceleration is one of the most important parameters affecting the efficiency of a TLCGD. In other words, it is found that the TLCGD's capability to reduce the RMS responses depends only on the frequency content of the ground acceleration, but its capability to reduce the maximum responses depends on both the frequency content and the pulse arrangement of the ground acceleration.
Mousavi, Seyed Amin; Zahrai, Seyed Mehdi; Bargi, Khosrow
Scaling theory in Tomonaga-Luttinger liquid with $1\\/r^\\\\beta$ type long-range interactions
We discuss effects of $1\\/r^\\\\beta$ type long-range (LR) interactions in a tight-binding model by utilizing the bosonization technique, renormalization group and conformal field theory (CFT). We obtain the low energy action known for Kibble's model which generates the mass gap in 3 dimension when $\\\\beta =1$, the Coulomb force case. In one dimension, the dispersion relations predict that the system
Hitoshi Inoue
Non-Fermi-liquid behavior in the fluctuating gap model: From the pole to a zero of the Green's function
We analyze the non-Fermi-liquid (NFL) behavior of the fluctuating gap model (FGM) of pseudogap behavior in both one and two dimensions. A detailed discussion of quasiparticle renormalization (Z-factor) is given, demonstrating a kind of marginal Fermi-liquid or Luttinger-liquid behavior and topological stability of the bare Fermi surface (the Luttinger theorem). In the two-dimensional case, we discuss the effective picture of the Fermi surface destruction both in the hot spot model of dielectric (AFM, CDW) pseudogap fluctuations and for the qualitatively different case of superconducting d-wave fluctuations, reflecting the NFL spectral density behavior and similar to that observed in ARPES experiments on copper oxides.
Kuchinskii, E. Z.; Sadovskii, M. V. [Russian Academy of Sciences, Institute for Electrophysics (Russian Federation)], E-mail: firstname.lastname@example.com
Towards an easy-to-use tuberculosis diagnosis through exhaled breath analysis: a liquid fluorimeter with an excitation at 265 nm
NASA Astrophysics Data System (ADS)
The struggle against tuberculosis is one of the World Health Organization priorities. Identifying in a short time, patients with active tuberculosis, would bring a tremendous improvement to the current situation. Recovering from this infectious and deadly disease (2 million of death per year) is possible with a correct diagnosis to give an appropriate treatment. Unfortunately, most common tuberculosis diagnoses have few drawbacks: - skin tests: not reliable at 100% and need an incubation of 2 days before the diagnosis, - blood tests: costly and sophisticated technology, - chest X-ray: the first step before the sputum tests used for a bacterial culture with a final diagnosis given within 2 weeks. A tuberculosis test based on exhaled breath analysis is a prospective and noninvasive solution, cheap and easy to use and to transport. This test lies on a fluoregenic detection of niacin, a well-known mycobacterium tuberculosis specific metabolite. In this paper, it is assumed that the selected probe is specific to niacin and that exhaled breath does not contain any interfering species. To address this problem, a fluorimeter is developed with a cheap and cooled CCD (? 2k$) as a sensor, to easily determine the suitable "fluorescent zone". In comparing aqueous solutions with and without niacin, 250 pM of niacin have been detected. With a commercial fluorimeter (Fluorolog from Horiba), only 200 nM of niacin are detected. The present detection remains 10 times above the estimated targeted value for a tuberculosis test. The excitation source is a LED, which typically emits 20 ?W at 265 nm through an optical fiber. The emission signal is detected around 545 nm. A typical light exposure lasts 700 seconds. Analysis of biomarkers with a liquid fluorimeter is generic and promising as health diagnosis.
Hue, J.; Dupoy, M.; Vignoud, S.; Ricaud, J. L.; Tran-Thi, T.; Karpe, S.; Novelli-Rousseau, A.; Mallard, F.
Ferromagnetic spin-orbital liquid of dipolar fermions in zigzag lattices
NASA Astrophysics Data System (ADS)
Two-component dipolar fermions in zigzag optical lattices allow for the engineering of spin-orbital models. We show that dipolar lattice fermions permit the exploration of a regime typically unavailable in solid-state compounds that is characterized by a spin-liquid phase with a finite magnetization and spontaneously broken SU(2) symmetry. This peculiar spin liquid may be understood as the Luttinger liquid of composite particles consisting of bound states of spin waves and orbital domain walls moving in an unsaturated ferromagnetic background. In addition, we show that the system exhibits a boundary phase transitions involving nonlocal entanglement of edge spins.
Sun, G.; Kolezhuk, A. K.; Santos, L.; Vekua, T.
Solvation-driven excited-state dynamics of [Re(4-Et-Pyridine)(CO)3(2,2'-bipyridine)]+ in imidazolium ionic liquids. A time-resolved infrared and phosphorescence study.
Excited-state dynamics of [Re(Etpy)(CO)3(bpy)]+ was studied in three imidazolium ionic liquids by time-resolved IR and emission spectroscopy on the picosecond to nanosecond time scale. Low-lying excited states were characterized by TD-DFT calculations, which also provided molecular dipole moment vectors in the relevant electronic states. TRIR spectra in ionic liquids show initial populations of two excited states: predominantly bpy-localized 3IL and 3MLCT, characterized by nu(CO) bands shifted to lower and higher frequencies, respectively, relative to the ground state. Internal conversion of 3IL to the lowest triplet 3MLCT occurred on a time scale commensurate with solvent relaxation. The nu(CO) IR bands of the 3MLCT state undergo a dynamic shift to higher wavenumbers during relaxation. Its three-exponential kinetics were determined and attributed to vibrational cooling (units of picoseconds), energy dissipation to the bulk solvent (tens of picoseconds), and solvent relaxation, the lifetime of which increases with increasing viscosity: [EMIM]BF4 (330 ps) < [BMIM]BF4 (470 ps) < [BMIM]PF6 (1570 ps). Time-resolved phosphorescence spectra in [BMIM]PF6 show a approximately 2 ns drop in intensity due to the 3IL --> 3MLCT conversion and a dynamic Stokes shift to lower energies with a lifetime decreasing from 1.8 ns at 21 degrees C to 1.1 ns at 37 degrees C, due to decreasing viscosity of the ionic liquid. It is proposed that solvent relaxation predominantly involves collective translational motions of ions. It drives the 3IL --> 3MLCT conversion, increases charge reorganization in the lowest excited-state 3MLCT, and affects vibrational anharmonic coupling, which together cause the dynamic shift of excited-state IR bands. TRIR spectroscopy of carbonyl-diimine complexes emerges as a new way to investigate various aspects of solvation dynamics, while the use of slowly relaxing ionic liquids offers new insight into the photophysics of Re(I) carbonyl polypyridyls. PMID:18373366
Blanco-Rodr�guez, Ana Maria; Ronayne, Kate L; Zalis, Stanislav; S�kora, Jan; Hof, Martin; Vlcek, Anton�n
A novel matrix method for coupled vibration and damping effect analyses of liquid-filled circular cylindrical shells with partially constrained layer damping under harmonic excitation
A novel matrix method is further developed for a liquid-filled circular cylindrical shell with partially constrained layer damping (CLD), which consists of treating liquid domain with Bessel function approach, and shell domain with transfer matrix equation based on a new set of first order matrix differential equation. In order to indicate its advantage to the finite element method (FEM), free
Yu Xiang; Liyun Yuan; Yuying Huang; Qiao Ni
NSDL National Science Digital Library
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NSDL National Science Digital Library
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Quasiparticles and Fermi liquid behaviour in an organic metal
Many organic metals display exotic properties such as superconductivity, spin-charge separation and so on and have been described as quasi-one-dimensional Luttinger liquids. However, a genuine Fermi liquid behaviour with quasiparticles and Fermi surfaces have not been reported to date for any organic metal. Here, we report the experimental Fermi surface and band structure of an organic metal (BEDT-TTF)3Br(pBIB) obtained using angle-resolved photoelectron spectroscopy, and show its consistency with first-principles band structure calculations. Our results reveal a quasiparticle renormalization at low energy scales (effective mass m*=1.9?me) and ?2 dependence of the imaginary part of the self energy, limited by a kink at ~50?meV arising from coupling to molecular vibrations. The study unambiguously proves that (BEDT-TTF)3Br(pBIB) is a quasi-2D organic Fermi liquid with a Fermi surface consistent with Shubnikov-de Haas results.
Kiss, T.; Chainani, A.; Yamamoto, H.M.; Miyazaki, T.; Akimoto, T.; Shimojima, T.; Ishizaka, K.; Watanabe, S.; Chen, C.-T.; Fukaya, A.; Kato, R.; Shin, S.
Cosmology with Liquid Mirror Telescopes.
National Technical Information Service (NTIS)
Liquid mirrors provide an exciting means to obtain large optical telescopes for substantially lower costs than conventional technologies. The liquid mirror concept has been demonstrated in the lab with the construction of a diffraction limited 1.5 m mirro...
D. W. Hogg B. K. Gibson P. Hickson
Quantum electronic liquid crystals
NASA Astrophysics Data System (ADS)
This thesis is devoted to an investigation of quantum electronic liquid crystal phases of matter. With the recent discovery of electronic phases that are neither isotropic liquids, nor crystalline solids, it is now vital to gain a comprehensive understanding of these intermediate "electronic liquid crystal" phases. Examples of these new phases include the highly anisotropic phases in quantum Hall systems, static stripes in cuprate superconductors and Fermi surface distortions in some heavy fermion and ruthenate systems. Owing to the strong correlations involved, such an investigation requires the use of non-perturbative methods and we choose to utilize the method of bosonization both in its one-dimensional form and its extension to greater than one-dimension. Our focus will be on two electronic liquid crystal phases representing two paradigms: one on the establishment of orientational order (the nematic phase) and the other on translational order (the smectic phase) both of which are intermediately ordered in comparison to a crystal. Using the method of bosonization, extended from one to two dimensions, we study the quantum nematic phase which arises due to shape (Pomeranchuk) instabilities of the Fermi surface of a Fermi liquid. Using this method, we demonstrate that in this phase and at the phase transition, the system of electrons is a non-Fermi liquid as defined by the existence of fermionic quasiparticles. At finite temperatures, we find that while order parameter correlations become long ranged as the system begins to order, fermionic correlations become correspondingly short ranged, a phenomena that has become known as 'local' quantum criticality. We also discuss translational ordering via an investigation of the quantum Hall smectic state which exhibits sliding symmetry: the ordered layers slide freely next to one another. We show, through renormalization group calculations, that such a symmetry causes the naive continuum approximation in the direction perpendicular to the stripes to break down. In particular, we show that the correct fixed point has the form of an array of sliding Luttinger liquids making sliding symmetry a dramatic features of this liquid crystalline phase. Similar considerations apply to all theories with sliding symmetries.
Lawler, Michael John
Magnetostrictive resonance excitation
The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.
Schwarz, Ricardo B. (Los Alamos, NM) [Los Alamos, NM; Kuokkala, Veli-Tapani (Tampere, FI) [Tampere, FI
Magnetostrictive resonance excitation
US Patent & Trademark Office Database
The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.
Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium.
Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)
Mukhopadhyay, N.C.
Laser Emission from Electron Beam Excited Znte.
National Technical Information Service (NTIS)
Laser emission was obtained from ZnTe excited by an electron beam. A peak output power of 90W with 8 percent overall power efficiency at a wavelength of 5280A was measured at liquid helium temperature. Lasers at liquid nitrogen temperature with an emissio...
C. E. Hurwitz
Saturated excitation microscopy with optimized excitation modulation.
Saturated excitation (SAX) microscopy utilizes the nonlinear relation between fluorescence emission and excitation under saturated excitation to improve the spatial resolution of confocal microscopy. In this study, we theoretically and experimentally investigate the saturation of fluorescence excitation under modulated excitation to optimize the excitation conditions for SAX microscopy. Calculation of the relationships between fluorescence and excitation intensity with different modulation frequencies reveals that the lifetime of the triplet state of the fluorescent probe strongly affects the strength of the demodulated fluorescence signals. We also find that photobleaching shows little dependence on the modulation frequency. These investigations allow us to determine the optimum excitation conditions, that is, the conditions providing sufficient fluorescence saturation without strong photobleaching. For a sample stained with ATTO Rho6G phalloidin, we estimate the optimal excitation conditions, which are produced with 50 kHz excitation modulation and a 50 ?sec pixel dwell time, and successfully perform three-dimensional imaging with sub-diffraction resolution. PMID:24488765
Yonemaru, Yasuo; Yamanaka, Masahito; Smith, Nicholas I; Kawata, Satoshi; Fujita, Katsumasa
Deconfined fractionally charged excitation in any dimensions
An exact incompressible quantum liquid is constructed at the filling factor 1/m{sup 2} in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m{sup 2}, the excitation has fractional charge e/m{sup 2}, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/m{sup n}. -- Highlights: ? We demonstrate that the fractionally-charged excitations can in principle exist in any dimensions. ? We compute the fractional charge of the excitations (e{sup ?}=e/m{sup D}). ? We demonstrate that the fractionally-charged excitation is in a deconfined phase.
Chern, Chyh-Hong, E-mail: email@example.com; Huang, Po-Hao; Lee, Hong-Hsi
Nuclear excited xenon flashlamp
The optical emissions of nuclear excited Xenon plasmas were investigated to determine basic parameters important to photolytic pumping of lasers. Gas mixtures of Helium-3 and Xenon were irradiated in the steady state mode in the University of Florida Training Reactor at neutron flux levels of about 10/sup 12//cm/sup 2/.s, generating a power density in the gas of approximately 3 milliwatts/cm/sup 3/. Optical emissions from the gas were primarily due to Xe/sub 2/* band emission at 172 nm with a few Xell lines in the visible and ir. Energy transfer from the /sup 3/He(n,p)T reaction to the Xe/sub 2/* 172 nm band was 67.0% +- 10%. High pressure gas mixtures (4 atm.) of Helium-3 and Xenon were irradiated in the pulse mode (250 ..mu..s FWHM) at the fast burst reactor at the Aberdeen Pulsed Radiation Facility at thermal neutron flux levels of about 10/sup 17//cm/sup 2/.s, generating a power density in the gas of about 1 kilowatt/cm/sup 3/. Optical emissions from the gas extended from the vacuum ultraviolet through the visible to the infrared, resembling a discharge excited lamp with a current density of about 1500 amp./cm/sup 2/. Such a lamp could pump a Neodymium YAG or liquid laser.
Cox, J.D.
Elementary excitations of sup 4 He clusters
The elementary excitations of {sup 4}He clusters containing N atoms are investigated by solving the equations of the random phase approximation (RPA) with a phenomenological effective interaction. The calculations were done for 40{le}N{le}728. The effects of the RPA correlations are explicitly discussed. Important deviations from the predictions of the liquid droplet model (LDM) are found up to N{approx equal}500 for the breathing compression mode and up to N{approx equal}100 for surface excitations. Sum rules for compression and surface excitations are also derived and discussed.
Casas, M. (Universitat de les Illes Balears, Palma de Mallorca (Spain)); Stringari, S. (Universita di Trento, Povo (Italy))
Non-Fermi-Liquid and Topological States with Strong Spin-Orbit Coupling
NASA Astrophysics Data System (ADS)
We argue that a class of strongly spin-orbit-coupled materials, including some pyrochlore iridates and the inverted band gap semiconductor HgTe, may be described by a minimal model consisting of the Luttinger Hamiltonian supplemented by Coulomb interactions, a problem studied by Abrikosov and collaborators. It contains twofold degenerate conduction and valence bands touching quadratically at the zone center. Using modern renormalization group methods, we update and extend Abrikosov�s classic work and show that interactions induce a quantum critical non-Fermi-liquid phase, stable provided time-reversal and cubic symmetries are maintained. We determine the universal power-law exponents describing various observables in this Luttinger-Abrikosov-Beneslavskii state, which include conductivity, specific heat, nonlinear susceptibility, and the magnetic Gruneisen number. Furthermore, we determine the phase diagram in the presence of cubic and/or time-reversal symmetry breaking perturbations, which includes a topological insulator and Weyl semimetal phases. Many of these phases possess an extraordinarily large anomalous Hall effect, with the Hall conductivity scaling sublinearly with magnetization ?xy�M0.51.
Moon, Eun-Gook; Xu, Cenke; Kim, Yong Baek; Balents, Leon
Growth and Excitation of Electrohydrodynamic Surface Waves
Waves on the surface of a capillary liquid jet stressed by a steady applied electric field will grow in space if the velocity of the jet is supercapillary. Experimental measurements of this growth rate confirm previous theoretical discussions. The excitation of these waves by means of an applied electric field with steady and time varying components is also studied theoretically,
Joseph M. Crowley
Ultrasonic resonators have a long tradition as microbalance, thin film monitor or sensor for liquid viscosity. The majority of the systems is based on piezoelectric transducers. However, chemical and biochemical detection using e.g. the Quartz Crystal Microbalance (QCM) reveal some limitations which require further examination of the acoustic wave excitation. Two sensor principles appreciate increasing interest: Lateral Field Excited (LFE)
Osorio Garcia; Maria Isabel; John F. Vetelino
ERIC Educational Resources Information Center
A secondary teacher describes how she has her students use liquid white enamel. With the enameling process, students can create lasting, exciting artwork. They can exercise an understanding of design and color while learning the value of careful, sustained craft skills. (RM)
Widmar, Marge
Fermi Liquid Berry Phase Theory of the Anomalous Hall Effect
NASA Astrophysics Data System (ADS)
Charged Fermi liquids with broken time-reversal symmetry have an intrinsic anomalous Hall effect that derives from the Berry phases accumulated by accelerated quasiparticles that move on the Fermi surface. The intrinsic Hall conductivity is given by a new fundamental geometric Fermi liquid formula that can be regarded as the derivative with respect to magnetic flux density of the Luttinger fomula relating the density of mobile charge carriers to the k-space volume enclosed by the Fermi surface. This formula can be derived by an integration-by-parts of the Karplus-Luttinger free-electron band-structure formula to yield a topological (QHE) part plus a geometrical part expressed completely at the Fermi surface, and which has a natural generalization to interacting Fermi liquid quasiparticles (QP's). The QP Berry phases are properties of the eigenstates of the (exact) single-particle Green's function at the Fermi surface, which is a Hermitian matrix with Bloch-state eigenvectors; the Berry phases derive from the variation on the Fermi surface of the spatially-periodic factor of the QP Bloch state that characterizes how the total QP amplitude is distributed among the different electronic orbitals in the unit cell. In the case of 3D ferromagnetic metals, the Berry phases derive from the interplay of exchange splitting with spin-orbit coupling (both must be present). Remarkably, the new formula also applies to Fermi-liquid analogs such as the 2D composite fermion (CF) fluid in the half-filled lowest Landau level: in this case, the QP is a bound electron+vortex composite and not a Bloch state. This QP structure varies on the CF Fermi surface in a way that exactly gives the expected result xycirc = e^2/2h, unaffected by any Fermi surface anisotropy, thus explaining how a quantized value of xycirc persists even though the CF Fermi liquid is not an incompressible FQHE state. The geometric anomalous Hall effect formula suggests a more intrinsic geometric description of the Fermi surface, where the Fermi vector kF(s) is only one of a number of properties that vary on a curved (D-1)-dimensional Fermi surface manifold parametrized by curvilinear coordinates s; other properties include the Berry curvature field F(s), quasiparticle mean free path l(s),etc. The new formula also naturally takes into account non-trivial (multiply-connected) Fermi surface topology and open orbits.
Haldane, F. D. M.
Acoustically excited heated jets. 1: Internal excitation
NASA Technical Reports Server (NTRS)
The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.
Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.
Current-fluctuation spectra of liquid rubidium
The mode-coupling theory has been worked out to calculate the longitudinal and transverse current-fluctuation spectra, the dynamical structure factor, and the dynamical as well as the static transport coefficients of liquid rubidium. The results are compared with experimental data. A detailed comparison of the excitation spectra of liquid rubidium with those of liquid argon is presented.
J. Bosse; W. G�tze; M. L�cke
Surface plasmon excitation in a hollow prism
NASA Astrophysics Data System (ADS)
We design a hollow prism to excite surface plasmon. The prism is coated with polymethyl methacrylate (PMMA) containing rhodamine 6G (Rh6G) and 30 nm thick Ag film on the inner surface. After filling the hollow prism with alcohol and CS2, we measured the reflectance angle spectrum and observed the significant absorption, which indicates that the localized surface plasmon is excited at the Ag-PMMA interface. This hollow prism structure may be used in analyzing the composition and reaction process of the liquid or gas at the same time.
Li, Jin; Zhang, Yundong; Li, Hanyang; Ma, Lei; Yua, Ping
Excitation of instability waves
NASA Astrophysics Data System (ADS)
A brief survey is given on artificial excitation of instability waves in parallel flows. There are basically two categories of unstable flows: (1) convectively unstable and (2) absolutely unstable flows. The perturbation level in convectively unstable flows, e.g., boundary layers and most free shear flows, depends on the excitation only. On the other hand, absolutely unstable flows, e.g., wake flows and hot jets, do maintain fluctuations independent of an exterior excitation. Finally, effects of non-parallel mean flow and of varying boundary conditons on instability wave excitation are discussed.
Bechert, D. W.
8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA
A Novel Liquid-Liquid Transition in Undercooled Ti-Zr-Ni Liquids
NASA Technical Reports Server (NTRS)
If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, T(sub l), finally 'freezing' into a glass below a characteristic temperature called the glass transition temperature, T(sub g). In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of H2O and Si. Such phase transitions have been predicted in some stable liquids, ie. above T(sub l) at atmospheric pressure, for SiO2 and BeF2, but these have not been verified experimentally. They have been observed in liquids of P, Si and C, but only under high pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity metallic liquid that is driven by an approach to a constant entropy configuration state and correlated with a growing icosahedral order in the liquid. A maximum in the specific heat at constant pressure, similar to what is normally observed near T(sub g), is reported for undercooled liquids of quasicrystal-forming Ti-Zr-Ni alloys. A two-state excitation model that includes cooperativity by incorporating a temperature-dependent excitation energy, fits the specific heat data well, signaling a phase transition. An inflection in the liquid density with decreasing temperature instead of a discontinuity indicates that this is not a typical first order phase transition; it could be a weakly first order or higher order transition. While showing many similarities to a glass transition, this liquid-liquid phase transition occurs in a mobile liquid, making it novel.
Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Bradshaw, R. C.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.
Magnetostrictive resonance excitation.
National Technical Information Service (NTIS)
The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection co...
R. B. Schwartz V. T. Kuokkala
Theory of Inelastic Scattering of Cold Neutrons from Liquid Helium
A measurement of the energy losses of monoenergetic neutrons scattered from liquid He II would permit a determination of the energy-versus-momentum relation for the elementary excitations (phonons and rotons) in the liquid. A major part of the scattering at a fixed angle arises from production or annihilation of a single excitation and appears as sharp lines in the energy spectrum.
Michael Cohen; Richard P. Feynman
Hydromagnet: A Self-Generating Liquid Conductor Electromagnet
A novel liquid electromagnet is investigated in which the exciting current is generated within the solenoid by forcing the liquid conductor radially inward through the space between two coaxial cylinders placed in an axial magnetic field. The tangential current thus generated within the flowing conductor adds to the initial applied field so that the device behaves like a self-excited, short-circuited
Henry H. Kolm; Osman K. Mawardi
Collective excitations on a surface of topological insulator
We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particles and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We develop quantum field-theoretical description of spin-plasmons in helical liquid and study their properties and internal structure. Value of spin polarization arising in the system with excited spin-plasmons is calculated. We also consider the scattering of spin-plasmons on magnetic and nonmagnetic impurities and external potentials, and show that the scattering occurs mainly into two side lobes. Analogies with Dirac electron gas in graphene are discussed. PACS: 73.20.Mf; 73.22.Lp; 75.25.Dk.
Sloshing motions in excited tanks
NASA Astrophysics Data System (ADS)
A fully non-linear finite difference model has been developed based on inviscid flow equations. Numerical experiments of sloshing wave motion are undertaken in a 2-D tank which is moved both horizontally and vertically. Results of liquid sloshing induced by harmonic base excitations are presented for small to steep non-breaking waves. The simulations are limited to a single water depth above the critical depth corresponding to a tank aspect ratio of hs/ b=0.5. The numerical model is valid for any water depth except for small depth when viscous effects would become important. Solutions are limited to steep non-overturning waves. Good agreement for small horizontal forcing amplitude is achieved between the numerical model and second order small perturbation theory. For large horizontal forcing, non-linear effects are captured by the third-order single modal solution and the fully non-linear numerical model. The agreement is in general good, both amplitude and phase. As expected, the third-order compared to the second-order solution is more accurate. This is especially true for resonance, high forcing frequency and mode interaction cases. However, it was found that multimodal approximate forms should be used for the cases in which detuning effects occur due to mode interaction. We present some test cases where detuning effects are evident both for single dominant modes and mode interaction cases. Furthermore, for very steep waves, just before the waves overturn, and for large forcing frequency, a discrepancy in amplitude and phase occurs between the approximate forms and the numerical model. The effects of the simultaneous vertical and horizontal excitations in comparison with the pure horizontal motion and pure vertical motion is examined. It is shown that vertical excitation causes the instability associated with parametric resonance of the combined motion for a certain set of frequencies and amplitudes of the vertical motion while the horizontal motion is related to classical resonance. It is also found that, in addition to the resonant frequency of the pure horizontal excitation, an infinite number of additional resonance frequencies exist due to the combined motion of the tank. The dependence of the non-linear behaviour of the solution on the wave steepness is discussed. It is found that for the present problem, non-linear effects become important when the steepness reaches about 0.1, in agreement with the physical experiments of Abramson [Rep. SP 106, NASA, 1966].
Frandsen, Jannette B.
Two types of quasiparticles excited in a Bose gas.
We present a novel approach for investigating the superfluid liquid 4He based on the proper use of the nonideal Bose gas model for dilute hard spheres. The results show that the presence of a macroscopic number of condensate atoms leads to the existence of a nonphysical branch, corresponding to density excitations, in addition to the continuous branch of the phonon-maxon-roton excitation spectrum. PMID:12857268
Minasyan, V N; Touryan, K J
Temperature and excitable cells
Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approach�by virtue of its thermodynamic nature�is by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology.
Fillafer, Christian; Schneider, Matthias F
Excitation Methods for Bridge Structures
This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.
Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.
Further Studies on Liquid Sloshing.
National Technical Information Service (NTIS)
Sloshing is especially of concern for LNG Carriers and large oil tankers because of their tank size and geometrical configurations and the likelihood of near-resonant excitation of the contained liquid. When a tank is under multi-degree-of-freedom excitat...
C. K. Lee M. C. Wu Y. K. Lou
Local structural excitations in model glasses
NASA Astrophysics Data System (ADS)
Structural excitations of model Lennard-Jones glass systems are investigated using the activation-relaxation technique (ARTn), which explores the potential energy landscape around a local minimum energy configuration by converging to a nearby saddle-point configuration. Performing ARTn results in a distribution of barrier energies that is single-peaked for well-relaxed samples. The present work characterizes such atomic-scale excitations in terms of their local structure and environment. It is found that, at zero applied stress, many of the identified events consist of chainlike excitations that can either be extended or ringlike in their geometry. The location and barrier energy of these saddle-point structures are found to correlate with the type of atom involved, and with spatial regions that have low Kelvin eigenshear moduli and are close to the excess free volume within the configuration. Such correlations are, however, weak and more generally the identified local structural excitations are seen to exist throughout the model glass sample. The work concludes with a discussion within the framework of ? and ? relaxation processes that are known to occur in the undercooled liquid regime.
Swayamjyoti, S.; L�ffler, J. F.; Derlet, P. M.
Excited species in the FBX dosimeter system
NASA Astrophysics Data System (ADS)
In the FBX dosimeter solution, the excitation of xylenol orange (XO) produces maximum emission at 550-575 nm both at room and liquid nitrogen temperatures (about 85%) having a lifetime of 0.20-0.36 ns. In addition, at room temperature there is an emission at 350 nm for the excitation at 260 nm (about 15%) having a longer lifetime of 3.71-4.01 ns. Benzoic acid (BA) has excitation at 284-295 nm and emission at 320-365 nm having a lifetime of 1.38 ns. In an aqueous solution containing 5�10 -3 mol dm -3 BA, 2�10 -4 mol dm -3 XO and 0.04 mol dm -3 H 2SO 4 there is no XO emission at 550 nm due to UV absorption at 260 nm by BA. In this solution, 2 emissions are observed near 350-360 nm, having lifetimes of 1.25 ns (89%) and 2.86 ns (11%). The wavelengths for the emission of XO and absorption of ferric-XO complex are nearly the same. Excited XO produces oxidation of ferrous ions and BA increases the chain length.
Gupta, B. L.
National Technical Information Service (NTIS)
The major accomplishment under this contract was the innovation of techniques for the production and detection of highly excited atoms (Rydberg atoms), and a series of studies on the properties of Rydberg atoms in strong electric fields. Partly as a resul...
D. Kleppner
PREFACE: Functionalized Liquid Liquid Interfaces
Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a
Hubert Girault; Alexei A. Kornyshev; Charles W. Monroe; Michael Urbakh
Wigner crystallization of single photons in cold Rydberg ensembles.
The coupling of weak light fields to Rydberg states of atoms under conditions of electromagnetically induced transparency leads to the formation of Rydberg polaritons which are quasiparticles with tunable effective mass and nonlocal interactions. Confined to one spatial dimension their low energy physics is that of a moving-frame Luttinger liquid which, due to the nonlocal character of the repulsive interaction, can form a Wigner crystal of individual photons. We calculate the Luttinger K parameter using density-matrix renormalization group simulations and find that under typical slow-light conditions kinetic energy contributions are too strong for crystal formation. However, adiabatically increasing the polariton mass by turning a light pulse into stationary spin excitations allows us to generate true crystalline order over a finite length. The dynamics of this process and asymptotic correlations are analyzed in terms of a time-dependent Luttinger theory. PMID:24074081
Otterbach, Johannes; Moos, Matthias; Muth, Dominik; Fleischhauer, Michael
Wigner Crystallization of Single Photons in Cold Rydberg Ensembles
NASA Astrophysics Data System (ADS)
The coupling of weak light fields to Rydberg states of atoms under conditions of electromagnetically induced transparency leads to the formation of Rydberg polaritons which are quasiparticles with tunable effective mass and nonlocal interactions. Confined to one spatial dimension their low energy physics is that of a moving-frame Luttinger liquid which, due to the nonlocal character of the repulsive interaction, can form a Wigner crystal of individual photons. We calculate the Luttinger K parameter using density-matrix renormalization group simulations and find that under typical slow-light conditions kinetic energy contributions are too strong for crystal formation. However, adiabatically increasing the polariton mass by turning a light pulse into stationary spin excitations allows us to generate true crystalline order over a finite length. The dynamics of this process and asymptotic correlations are analyzed in terms of a time-dependent Luttinger theory.
Otterbach, Johannes; Moos, Matthias; Muth, Dominik; Fleischhauer, Michael
Photothermal excitation setup for a modified commercial atomic force microscope.
High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and to maintain the low noise level of the original setup with a typical deflection noise density of about 15 fm/?[Hz] measured in aqueous solution. The success of the modification is illustrated by a comparison of the resonance spectra obtained with piezoelectric and photothermal excitation. The performance of the systems is demonstrated by presenting high-resolution images on bare calcite in liquid as well as organic adsorbates (Alizarin Red S) on calcite with simultaneous atomic resolution of the underlying calcite substrate. PMID:24593367
Adam, Holger; Rode, Sebastian; Schreiber, Martin; Kobayashi, Kei; Yamada, Hirofumi; K�hnle, Angelika
Thermally driven acoustic oscillations, Part VI: Excitation and power
Summary In continuation of previous work in the field of thermally driven acoustic oscillations, the problem of excited oscillations is treated and presented in detail for the Sondhauss tube and for gas-liquid oscillations. The problem of the maximally attainable mechanical power from a Sondhauss tube is discussed.
Ulrich A. Mfiller; Nikolaus Rott
Aperture excited dielectric antennas
NASA Technical Reports Server (NTRS)
The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.
Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.
Nonlinear excitations in lattices
NASA Astrophysics Data System (ADS)
We analyze some of the properties of nonlinear excitations occurring in lattices such as polarons, bipolarons or discrete breathers (DBs). While polarons and bipolarons are the result of the self-trapping of one or two electronic carriers by the lattice distortion they generate, DBs occur in networks of identical non-harmonic oscillators as exact solutions to the equations of motion that are both time-periodic and spatially localized. In certain limits, these excitations may be described by a common class of models: the Discrete Nonlinear Schrodinger Equation and its generalizations. We first use an exact perturbative expansion to derive the bipolaronic phase diagram of the 1D adiabatic Holstein-Hubbard model (HH) in the strong coupling limit. In the second part of the thesis we study DBs on d-dimensional cubic lattices with arbitrary power nonlinearity. We compare the exact results to an exponential ansatz approach and to the solution to the Single Nonlinear Impurity (SNI) model. We show that DB excitation thresholds can be evaluated explicitly in the limit of high nonlinearity, and we prove a conjecture by Bustamante and Molina [PRB 62, 15287 (2000)] that the limiting value of the SNI bound state energy is universal as the nonlinearity tends to infinity.
Zhou, Jun
Harmonically excited orbital variations
Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.
Morgan, T.
Apparatus for photon excited catalysis
NASA Technical Reports Server (NTRS)
An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.
Saffren, M. M. (inventor)
A Liquid-Liquid Transition in an Undercooled Ti-Zr-Ni Liquid
NASA Technical Reports Server (NTRS)
If crystallization can be avoided, liquids enter a metastable (undercooled) state below their equilibrium liquidus temperatures, TI, finally freezing into a glass below a characteristic temperature called the glass transition temperature, T,. In rare cases, the undercooled liquid may undergo a liquid-liquid phase transition (liquid polymorphism) before entering the glassy state. This has been suggested from experimental studies of HzO and Si4. Such phase transitions have been predicted in some stable liquids, i.e. above TI at atmospheric pressure, for Si02 and BeF;, but these have not been verified experimentally. They have been observed in liquids of P7, Sis and C9, but only under high pressure. All of these transitions are driven by an anomalous density change, i.e. change in local structure, with temperature or pressure. In this letter we present the first experimental evidence for a phase transition in a low viscosity liquid that is not driven by an anomalous density change, but by an approach to a constant configuration state. A maximum in the specific heat at constant pressure, similar to what is normally observed near T,, is reported here for undercooled low viscosity liquids of quasicrystal- forming Ti-Zr-Ni alloys. that includes cooperativity, by incorporating a temperature dependent excitation energy fits the data well, signaling a phase transition.
Lee, G. W.; Gangopadhyay, A. K.; Kelton, K. F.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.
Do liquidity measures measure liquidity?
Given the key role of liquidity in finance research, identifying high quality proxies based on daily (as opposed to intraday) data would permit liquidity to be studied over relatively long timeframes and across many countries. Using new measures and widely employed measures in the literature, we run horseraces of annual and monthly estimates of each measure against liquidity benchmarks. Our
Ruslan Y. Goyenko; Craig W. Holden; Charles A. Trzcinka
Electronic excitations of adsorbed CO
NASA Astrophysics Data System (ADS)
Electronic excitations of CO adsorbed on Ir(111) are probed by energy dependent angle-resolved electron energy loss spectroscopy. The results are related to other CO adsorption systems and to recent theoretical investigations. Triplet excitations as well as charge transfer excitations are identified in the 5-7 eV loss region. Intramolecular singlet excitations are most likely to be responsible for the loss features at 13-15 eV. Excitations involving the 5? orbital of chemisorbed CO are complex and distinctly different in character from their respective gas phase counterparts.
Netzer, F. P.; Mack, J. U.; Bertel, E.; Matthew, J. A. D.
Electronic excitations of adsorbed CO
NASA Astrophysics Data System (ADS)
Electronic excitations of CO adsorbed on Ir(111) are probed by energy dependent angle-resolved electron energy loss spectroscopy. The results are related to other CO adsorption systems and to recent theoretical investigations. Triplet excitations as well as charge transfer excitations are identified in the 5-7 eV loss region. Intramolecular singlet excitations are most likely to be responsible for the loss features at 13-15 eV. Excitations involving the 5? orbital of chemisorbed CO are complex and distinctly different in character from their respective gas phase counterparts.
Netzer, F. P.; Mack, J. U.; Bertel, E.; Matthew, J. A. D.
Composite fermion excitations in fractional quantum Hall systems
In two dimensional systems in a strong magnetic field, electrons can be transformed into composite Fermions (CF) by attaching to each a fictitious flux tube (carrying flux {Phi}) and fictitious charge q, where the product q{sup {Phi}} is a multiple of 2 {Pi}. In the mean field approximation, this transformation converts a fractionally filled electron Landau level into an integrally filled CF Landau level. This integrally filled CF Landau level corresponds to the ground state of a Laughlin incompressible fluid. Excited states are described by the n{sub QE} and n{sub QH}, the numbers of quasielectron and quasihole CF excitations. For N electrons on the surface of a sphere the energy and angular momentum of a quasihole (or quasielectron) are {var_epsilon}{sub QH} and l{sub QH}=1/2(N+n{sub QH}-n{sub QE}-1) (or {var_epsilon}{sub QE} and l{sub QE}=l{sub QH}+1). The lowest energy sector of the energy spectrum contains the minimum number of CF excitations consistent with the value of N and the degeneracy of the lowest Landau level, 2S+1. The first excited sector contains one additional QE-QH pair. The total angular momentum L is obtained by adding the angular momenta of QE excitations and QH excitations treated as distinguished sets of Fermions. In the absence of CF interactions, all states containing n{sub QE} quasielectrons and n{sub QH} quasiholes are degenerate. The interaction between CF excitations partially removes this degeneracy. The interactions between CF excitations can be determined by comparing exact numerical results for N electrons with the CF picture. This amounts to constructing a Fermi liquid theory of CF excitations, and should allow the study of low lying excitations of systems with much larger values of N than can be treated numerically.
Quinn, J.J. [Univ. of Tennessee, Knoxville, TN (United States)
NSDL National Science Digital Library
Investigate how atoms can be excited to give off radiation (photons) with models of electron energy diagrams. Explore the effects of energy levels in atoms through interactive computer models. Learn about the different electron orbitals of an atom, and explore three-dimensional models of the atoms. Learn about photons and why they are emitted, and gain an understanding of the link between energy levels and photons as you discover how an atom�s electron configuration affects which wavelengths of light it will admit or absorb.
Consortium, The C.
Fluorescent optical liquid level sensor
A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.
Weiss, Jonathan D. (Albuquerque, NM) [Albuquerque, NM
Excitability in Dictyostelium development
NASA Astrophysics Data System (ADS)
Discovering how populations of cells reliably develop into complex multi-cellular structures is a key challenge in modern developmental biology. This requires an understanding of how networks at the single-cell level, when combined with intercellular signaling and environmental cues, give rise to the collective behaviors observed in cellular populations. I will present work in collaboration with the Gregor lab, showing that the signal-relay response of starved cells of the amoebae Dictyostelium discoideum can be well modeled as an excitable system. This is in contrast to existing models of the network that postulate a feed-forward cascade. I then extend the signal-relay model to describe how spatial gradient sensing may be achieved via excitability. One potential advantage of relying on feedback for gradient sensing is in preventing ``cheaters'' that do not produce signals from taking over the population. I then combine these models of single-cell signaling and chemotaxis to perform large-scale agent-based simulations of aggregating populations. This allows direct study of how variations in single-cell dynamics modify population behavior. In order to further test this model, I use the results of a screen for mutant cell lines that exhibit altered collective patterns. Finally, I use an existing FRET movie database of starved cell populations at varying cell densities and dilution rates to study heterogeneity in repeated spatio-temporal activity patterns.
Schwab, David
LSPR properties of metal nanoparticles adsorbed at a liquid-liquid interface.
Unlike the solid-air and solid-liquid interfaces, the optical properties of metal nanoparticles adsorbed at the liquid-liquid interface have not been theoretically exploited to date. In this work, the three dimensional finite difference time domain (3D-FDTD) method is employed to clarify the localized surface plasmon resonance (LSPR) based optical properties of gold nanoparticles (NPs) adsorbed at the water-oil interface, including near field distribution, far field absorption and their relevance. The LSPR spectra of NPs located at a liquid-liquid interface are shown to differ significantly from those in a uniform liquid environment or at the other interfaces. The absorption spectra exhibit two distinct LSPR peaks, the positions and relative strengths of which are sensitive to the dielectric properties of each liquid and the exact positions of the NPs with respect to the interface. Precise control of the particles' position and selection of the appropriate wavelength of the excitation laser facilitates the rational design and selective excitation of localized plasmon modes for interfacial NPs, a necessary advance for the exploration of liquid-liquid interfaces via surface enhanced Raman spectroscopy (SERS). According to our calculations, the SERS enhancement factor for Au nanosphere dimers at the water-oil interface can be as high as 10(7)-10(9), implying significant promise for future investigations of interfacial structure and applications of liquid-liquid interfaces towards chemical analysis. PMID:23376970
Yang, Zhilin; Chen, Shu; Fang, Pingping; Ren, Bin; Girault, Hubert H; Tian, Zhongqun
Multiphoton excitation of organic chromophores in microbubble resonators
NASA Astrophysics Data System (ADS)
We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW.
Cohoon, Gregory A.; Kieu, Khanh; Norwood, Robert A.
US Patent & Trademark Office Database
A process that provides the ability to incorporate a self exciting loop (SEL) algorithm into a digital LLRF system. The present digital SEL provides for conversion from the Cartesian domain to the Polar domain, wherein most signal processing is accomplished, and back to Cartesian. By handling most signal processing in the Polar (phase & amplitude) domain, a perfect amplitude limiter can be realized and simpler logic operations can be used. When operational, cavity recovery from faults will be tuner-less. At high gradients, .about.20 MV/m, like those needed for the upgraded cryomodules, the Lorentz detuning will be many bandwidths, making cavity turn-on problematic with out some tuner based compensation or other algorithmic solution. The present SEL solves this problem and allows cavity recovery from cryogenic trips, wherein cavities have been known to detune 1000's of Hz. Other applications such has He processing can also be implemented in situ without additional electronics.
The neuromuscular junctions and nonjunctional sarcolemmas of mammalian skeletal muscle fibers were studied by conventional thin-section electron microscopy and freeze-fracture techniques. A modified acetylcholinesterase staining procedure that is compatible with light microscopy, conventional thin-section electron microscopy, and freeze-fracture techniques is described. Freeze-fracture replicas were utilized to visualize the internal macromolecular architecture of the nerve terminal membrane, the chemically excitable neuromuscular junction postsynaptic folds, and the electrically excitable nonjunctional sarcolemma. The nerve terminal membrane is characterized by two parallel rows of 100�110-� particles which may be associated with synpatic vesicle fusion and release. On the postsynpatic folds, irregular rows of densely packed 110�140-� particles were observed and evidence is assembled which indicates that these large transmembrane macromolecules may represent the morphological correlate for functional acetylcholine receptor activity in mammalian motor endplates. Differences in the size and distribution of particles in mammalian as compared with amphibian and fish postsynaptic junctional membranes are correlated with current biochemical and electron micrograph autoradiographic data. Orthogonal arrays of 60-� particles were observed in the split postsynaptic sarcolemmas of many diaphragm myofibers. On the basis of differences in the number and distribution of these "square" arrays within the sarcolemmas, two classes of fibers were identified in the diaphragm. Subsequent confirmation of the fiber types as fast- and slow-twitch fibers (Ellisman et al. 1974. J. Cell Biol. 63[2, Pt. 2]:93 a. [Abstr.]) may indicate a possible role for the square arrays in the electrogenic mechanism. Experiments in progress involving specific labeling techniques are expected to permit positive identification of many of these intriguing transmembrane macromolecules.
Rash, John E.; Ellisman, Mark H.
Optically excited states in positronium
NASA Technical Reports Server (NTRS)
Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.
Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.
NSDL National Science Digital Library
In this math lesson, learners analyze the density of liquids in order to explore linear functions. Learners gather mass and volume data for two mystery liquids, oil and water, and then use the data to explore linear functions. Learners discuss the physical meaning of the slopes and y-intercepts of the various lines they create from scatterplots.
Liquid metal thermoacoustic engine
We are studying a liquid metal thermoacoustic engine both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts. A sound wave is usually thought of as consisting of pressure oscillations, but always attendant to the pressure oscillation are temperature oscillations. The combination produces a rich variety of ''thermoacoustic'' effects. These effects are usually so small that they are never noticed in everyday life; nevertheless under the right circumstances they can be harnessed to produce powerful heat engines, heat pumps, and refrigerators. In our liquid metal thermoacoustic engine, heat flow from a high temperature source to a low temperature sink generates a high-amplitude standing acoustic wave in liquid sodium. This acoustic power is converted to electric power by a simple magnetohydrodynamic effect at the acoustic oscillation frequency. We have developed a detailed thermoacoustic theory applicable to this engine, and find that a reasonably designed liquid sodium engine operating between 700/sup 0/C and 100/sup 0/C should generate about 60 W/cm/sup 2/ of acoustic power at about 1/3 of Carnot's efficiency. Construction of a 3000 W-thermal laboratory model engine has just been completed, and we have exciting preliminary experimental results as of the time of preparation of this manuscript showing, basically, that the engine works. We have also designed and built a 1 kHz liquid sodium magnetohydrodynamic generator and have extensive measurements on it. It is now very well characterized both experimentally and theoretically. The first generator of its kind, it already converts acoustic power to electric power with 40% efficiency. 16 refs., 5 figs.
Swift, G.W.; Migliori, A.; Wheatley, J.C.
Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future.
Tawfic, Qutaiba A.; Kausalya, Rajini
Numerical simulation of liquid sloshing in three-dimensional tanks
NASA Astrophysics Data System (ADS)
Liquid sloshing in 3D dynamically excited containers is simulated by means of the panel method derived from the boundary-integral technique. Free-surface profiles and tank-wall pressures are determined for spherical tanks under forced sway- and pitch-mode excitation. An incremental multistep treatment gives results on the effects of sloshing that are numerically stable.
Hwang, J. H.; Kim, I. S.; Seol, Y. S.; Lee, S. C.; Chon, Y. K.
Modal analysis of Lamb wave generation in elastic plates by liquid wedge transducers
A modal analysis is presented to describe the excitation of Lamb waves in an elastic plate using a liquid wedge transducer. Analytical expression for the displacement of a given mode is derived for the excitation by a uniform bounded beam. In contrast to previous studies, the contribution of the reflected wave is included in the input exciting forces using a
X. Jia
Investigation of Diffusion of Optical Excitations in Divalent Thulium IONS:STRONTIUM-FLUORIDE.
NASA Astrophysics Data System (ADS)
The migration of optical excitations of divalent thulium ions at low concentration in strontium fluoride are studied using optical techniques. Two types of excitation are studied. The first type is excitation of the metastable E_{5/2} state of thulium. Upper limits are placed on the diffusion length of this excitation of 8.6 nm at 300^circK and 20 nm at 2^circK for sample concentrations less than.026% Tm^{2+ }. These limits are in agreement with a model in which transport is due to optical magnetic dipole-dipole interactions and results in excitation transport over distances of about the mean separation between ions (3.5 nm) at liquid helium temperatures and no transport of excitation at room temperature. Migration of excitation of the ground state hyperfine sublevels of divalent thulium is studied at low temperature using optical techniques by taking advantage of the magneto -optical activity of these sublevels. A diffusion length of a few microns is predicted for this excitation due to magnetic dipole-dipole interactions between nearest neighbor ion pairs. The excitation is observed to have a diffusion length less than 2 microns, however the size of the laser induced population grating in these sublevels is less than 12% of the value predicted by theory. This indicates rapid relaxation of the spin excitation over short timescales and is believed to be due to spin-lattice relaxation during the time following the laser excitation pulse that the lattice is not at thermal equilibrium.
D'Amato, Francis Xavier
Rotation of an inclined surface on which Helix is creeping straight upward, such that the axis of the animal is turned at a right angle to its previous position, but in the same plane, leads to negatively geotropic orientation after a measurable latent period or reaction time. The duration of the latent period is a function of the slope of the surface. The magnitude of the standard deviation of the mean latent period is directly proportional to the mean latent period itself, so that the relative variability of response is constant. The dependence of reaction time upon extent of displacement from symmetrical orientation in the gravitational field is found also by tilting the supporting surface, without rotation in the animal's own plane. On slopes up to 55�, the relation between latent period and the sine of the slope is hyperbolic; above this inclination, the latent period sharply declines. This change in the curve is not affected by the attachment of moderate loads to the snail's shell (up to 1/3 of its own mass), and is probably a consequence of loss of passive stable equilibrium when rotated. When added loads do not too greatly extend the snail's anterior musculature, the latent period for the geotropic reaction is decreased, and, proportionately, its ?. These facts are discussed from the standpoint that geotropic excitation in these gasteropods is due to impressed muscle-tensions.
Hoagland, H.; Crozier, W. J.
Anomalously sharp phonon excitations in 3He droplets
NASA Astrophysics Data System (ADS)
The absorption spectra of the S1<--S0 electronic transition of a glyoxal molecule (C2H2O2) embedded inside a pure Fermionic 3He droplet shows a sharp zero-phonon excitation line followed by a slowly decreasing wing extending to higher frequencies. Superimposed upon the wing, a small but sharp peak is observed at ?E=0.99 meV. The wing is shown to be due to the continuum of particle-hole pair excitations while the sharp peak results from the excitation of localized phonons of the snowball shell of 3He atoms surrounding the chromophore molecule. The exceptional sharpness of the observed phonon peak (at least 10 times narrower than the ordinary bulk phonon peak at the same energy) is attributed to the localization associated with Friedel-like oscillations of the 3He liquid density.
Poertner, N.; Toennies, J. P.; Vilesov, A. F.; Benedek, G.; Hizhnyakov, V.
Get excited: Reappraising pre-performance anxiety as excitement.
Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24364682
Brooks, Alison Wood
NASA Astrophysics Data System (ADS)
How far can one supercool a liquid before it crystallizes? How much can one stretch it before cavitation occurs ? In order to answer such questions, we have studied liquid helium, a model system. In this review, we show the limitations of the elementary 'standard nucleation theory'. We then show that the existence of 'spinodal' limits needs to be considered in the framework of 'density functional' methods. We also briefly consider the possibility of nucleation by quantum tunnelling. The main emphasis is on cavitation and crystallization in liquid helium, but we also mention several connections with more classical systems, in particular water.
Balibar, S.; Caupin, F.
Excitation of microseisms: views from the normal-mode approach
NASA Astrophysics Data System (ADS)
Non-linear interaction of ocean waves is a widely accepted mechanism of microseism excitation for frequencies approximately between 0.05 and 0.5 Hz. Longuet-Higgins published the most influential paper on this subject in 1950 and his main contributions can be summarized in two points; the first is on the double-frequency mechanism and the second is on the dependency of excitation on ocean depth. The two results were derived for different media, the first point for an incompressible liquid (ocean) and the second point for a compressible liquid layer over an elastic half-space. The two features naturally come out in the normal-mode formulae. We note, however, that the use of the Longuet-Higgins formula, that showed efficiency of excitation based on ocean depth, is not suitable for interpreting land-based observations because his formula was for displacement at ocean bottom. Reevaluation of this dependency for a land-based observation shows similar results for the depth of maximum excitation, but the sharpness of this peak is reduced significantly. Some recent observational studies tried to identify the source area of excitation by using this ocean-depth dependency, but such a result needs to be revised to a larger source region according to our results. We confirm that the maximum excitation of microseisms exists and occurs when the ocean depth is about 2.7 km. It is thus not surprising to find an efficient pelagic source for microseisms, although existence of the wave-wave interaction in the source region is essential.
Tanimoto, Toshiro
NSDL National Science Digital Library
Young learners investigate and observe the properties of three liquids -- water, vegetable oil, and corn syrup. They use their senses to collect data and ask and answer questions. This lesson for young learners introduces the scientific process.
Janulaw, Sharon
NASA Technical Reports Server (NTRS)
Liquid-penetrant inspection is discussed for surface defects in solids. The principle advantages are considered to be its simplicity and economy. The techniques and penetrants are described along with the developers. Commercially available equipment is also described.
Pasley, R. L.
This book contains the following six chapters: Characteristics of Petroleum Products; Behavior of Petroleum Products; Extinguishing Agents; Preplanning for Petroleum-Liquid Emergencies; Strategies and Tactics; and Termination Procedures.
Hawthorne, E.
Sound Transmission in Liquid-Viscoelastic Multilayer Media.
National Technical Information Service (NTIS)
An expression for the acoustic response of a liquid layer overlying a multilayer viscoelastic medium is determined. The excitation is provided by a point source in the liquid layer. In this boundary-value problem the theories of fluid dynamics and elastic...
G. K. Stewart
Vibrational Excitation in Molecular Collisions
NASA Astrophysics Data System (ADS)
The collision energy dependence of the total cross sections for state resolved translation to vibration energy transfer was measured for several neutral systems. Measurements were made for vibrationally inelastic collisions of iodine with helium, neon, and hydrogen isotopes, as well as collisions of aniline and paradifluorobenzene with helium, all in the thermal energy range. Our new experimental technique uses pulsed supersonic molecular beams for initial state selection, crossed at a variable intersection angle for kinematic, continuously tunable collision energy selection. The scattered products are state-selectively detected in the intersection region by laser induced fluoroscence. The iodine cross section energy dependences are approximately linear, quadratic, and cubic for v = 0 to 1, 2, and 3 excitations respectively, as expected from a classical-quantal correspondence principle model. Extreme mode specificity was observed in the polyatoms as only 3 of about 20 energetically accessible vibrations were observed to be collisionally excited. In aniline, the 2 lowest frequency modes were excited. The cross section for single quantum excitations of the inversion mode of the amine group is a strongly decreasing function over the 20 to 250 meV collision energy range. The other observed mode, an out-of-plane bend of the amine group shows a linear onset at threshold for single quantum excitations. The only vibration excited in paradifluorobenzene was the lowest frequency, out-of-plane fluorine bend. Excitation of 1 and 2 quanta was observed. The cross sections both have approximately linear onset at threshold.
Hall, Gregory
Radioactivity Induced by Nuclear Excitation I. Excitation by Neutrons
It is shown that the 4.1-hr. period of indium can be produced by nuclear excitation of indium and is to be attributed to an excited metastable state, In115,* of the stable In115. This result is obtained by studying the radioactivity produced in indium by neutrons of different energy distributions and by studying the chain reactions produced in cadmium by fast
M. Goldhaber; R. D. Hill; Leo Szilard
New developments in catalysis using ionic liquids
Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents for catalysis. Being composed entirely of ions, they possess negligible vapour pressures, and the wide range of possible cations and anions means that other solvent properties may be easily controlled. There is currently great interest in the use of these materials as solvents for
Charles M. Gordon
Connecting Chemical Dynamics in Gases and Liquids
Modern ultrafast spectroscopic techniques provide new opportunities to study chemical reaction dynamics in liquids and hold the possibility of obtaining much of the same detailed information available in gases. Vibrational energy transfer studies are the most advanced of the investigations and demonstrate that it is possible to observe state-specific pathways of energy flow within a vibrationally excited molecule (intramolecular vibrational
Christopher G. Elles; F. Fleming Crim
Localized excitations and their thresholds
We propose a numerical method for identifying localized excitations in discrete nonlinear Schrodinger type models. This methodology, based on the application of a nonlinear iterative version of the Rayleigh-Ritz variational principle yields breather excitations in a very fast and efficient way in one or higher spatial dimensions. The typical convergence properties of the method are found to be super-linear. The usefulness of this technique is illustrated by studying the properties of the recently developed theoretical criteria for the excitation power thresholds for nonlinear modes. PMID:11088275
Kevrekidis; Rasmussen; Bishop
Multiphonon excitations in 62Zn
NASA Astrophysics Data System (ADS)
We studied excited states in 62Zn up to an excitation energy of 5.5 MeV via the 61Ni( 3He, 2n ?) reaction at the Cologne Tandem accelerator with the high-efficiency HORUS cube spectrometer. We identified several multi-phonon excitations, especially two fragments of the one-phonon mixed-symmetry state 21,MS+ based on effective M1 and E2 transition strengths. The quantities were obtained from ?? angular correlation and Doppler-shift measurements. Shell-model calculations performed for 62Zn give clear support for the fragmentation of the one-phonon mixed-symmetry 21,MS+ state. The assumption of 62Zn being a vibrator-like nucleus is supported by calculations of excitation energies and E2 and M1 transition strengths within the U(5) limit of the neutron-proton Interacting Boson Model.
Albers, M.; M�cher, D.; Bernards, C.; Blazhev, A.; Fransen, C.; Heinze, S.; Jolie, J.; Lisetskiy, A.; Petkov, P.; Radeck, D.; Zell, K. O.
Liquid chromatographic assay of dityrosine in human cerebrospinal fluid
A micro-scale method for separation and measurement of dityrosine in human cerebrospinal fluid (CSF) is described utilizing liquid-liquid extraction and ion-paired, reversed-phase high-performance liquid chromatography with fluorimetric detection. A mobile phase containing 1-heptanesulfonic acid linearly increased in methanol from 0 to 100% over 30 min allows the resolution of dityrosine from other fluorescent compounds with excitation at 285 nm and
Maged Abdelrahim; Elena Morris; Jeannean Carver; Stephen Facchina; Alison White; Ajay Verma
Collisional excitation of interstellar formaldehyde
NASA Technical Reports Server (NTRS)
Previous calculations for rates of excitation of ortho-H2CO by collisions with He have been extended to higher rotational levels and kinetic temperatures to 80 K. Rates for para-H2CO have also been computed. Pressure-broadening widths for several spectral lines have been obtained from these calculations and are found to agree with recent data within the experimental uncertainty of 10%. Excitation of formaldehyde by collisions with H2 molecules is also discussed.
Green, S.; Garrison, B. J.; Lester, W. A., Jr.; Miller, W. H.
Electrostatic Tuning of Cellular Excitability
Abstract Voltage-gated ion channels regulate the electric activity of excitable tissues, such as the heart and brain. Therefore, treatment for conditions of disturbed excitability is often based on drugs that target ion channels. In this study of a voltage-gated K channel, we propose what we believe to be a novel pharmacological mechanism for how to regulate channel activity. Charged lipophilic substances can tune channel opening, and consequently excitability, by an electrostatic interaction with the channel's voltage sensors. The direction of the effect depends on the charge of the substance. This was shown by three compounds sharing an arachidonyl backbone but bearing different charge: arachidonic acid, methyl arachidonate, and arachidonyl amine. Computer simulations of membrane excitability showed that small changes in the voltage dependence of Na and K channels have prominent impact on excitability and the tendency for repetitive firing. For instance, a shift in the voltage dependence of a K channel with ?5 or +5 mV corresponds to a threefold increase or decrease in K channel density, respectively. We suggest that electrostatic tuning of ion channel activity constitutes a novel and powerful pharmacological approach with which to affect cellular excitability.
Borjesson, Sara I.; Parkkari, Teija; Hammarstrom, Sven; Elinder, Fredrik
Measurement of acoustic properties of liquid using liquid flow SH-SAW sensor system
The SH-SAW resonator having narrow bandwidth and higher Q value has been used for sensing the properties in ionic and viscosity of liquid. The surface acoustic waves with the shear horizontal displacement (SH-SAW) are excited on a piezoelectric substrate; 36 rotated Y cut X prop. LiTaO3 (36 YX LiTaO3) and the liquid flow sensing system was constructed by using two-port
T Nomura; A Saitoh; Y Horikoshi
Picosecond study of electronically excited singlet states of nucleic acid components
NASA Astrophysics Data System (ADS)
The method of picosecond kinetic Spectroscopy has been used to measure some characteristics of excited singlet states of nucleic acid components in liquid aqueous solutions. It has been shown that the times ?1 or non-radiative relaxation of the excited electronic stale S1 to the ground state S0 for uracil, uridine and thymine lie in the range 4 � 2 ps, while for adenine and cytosine ?1 XXX 4 ps.
Oraevsky, A. A.; Sharkov, A. V.; Nikogosyan, D. N.
Van der Pol type self-excited micro-cantilever probe of�atomic force microscopy
For usage of noncontact atomic force microscopy (NC-AFM) in a liquid environment, we propose a �van der Pol�-type self-excited\\u000a cantilever probe whose steady state amplitude can be controlled to be sufficiently small so as not to damage the surface of\\u000a the observation object. The self-exciting technique for the micro cantilever probe has become a powerful tool for obtaining\\u000a atomically resolved
Hiroshi Yabuno; Hiroyuki Kaneko; Masaharu Kuroda; Takeshi Kobayashi
Forced torsion pendulum for studies of interactions at solid�liquid interface
A forced torsion pendulum for measurement of friction forces between solid surfaces and flowing liquid environments was designed and assembled. The apparatus utilizes the axial Couette flow generated in removable cylinder specimen cell filled with a liquid. The cell is co-axial with the pendulum shaft and the liquid flow is excited within a thin layer adjacent to the inner wall
Y. Yagodzinskyy; L. Straka; H. H�nninen
Finite element analysis of fluid-structure interaction effect on liquid retaining structures due to sloshing
Fluid-structure interaction problems, which may be categorized into different types, have attracted the attention of engineers because of their numerous practical applications. Sloshing of liquid in a liquid filled container subjected to external excitations and coupled interaction between the liquid and container wall due to sloshing is one such problem. The focus of the present paper is on the development
S. Subhash Babu; S. K. Bhattacharyya
Quantum Spin Liquids and Fractionalization
NASA Astrophysics Data System (ADS)
This chapter discusses quantum antiferromagnets which do not break any symmetries at zero temperature - also called "spin liquids" - and focuses on lattice spin models with Heisenberg-like (i.e. SU(2)-symmetric) interactions in dimensions larger than one. We begin by discussing the Lieb-Schultz-Mattis theorem and its recent extension to D > 1 by Hastings (2004), which establishes an important distinction between spin liquids with an integer and with a half-integer spin per unit cell. Spin liquids of the first kind, "band insulators", can often be understood by elementary means, whereas the latter, "Mott insulators", are more complex (featuring "topological order") and support spin-1/2 excitations (spinons). The fermionic formalism (Affleck and Marston, 1988) is described and the effect of fluctuations about mean-field solutions, such as the possible creation of instabilities, is discussed in a qualitative way. In particular, we explain the emergence of gauge modes and their relation to fractionalization. The concept of the projective symmetry group (X.-G. Wen, 2002) is introduced, with the aid of some examples. Finally, we present the phenomenology of (gapped) short-ranged resonating-valence-bond spin liquids, and make contact with the fermionic approach by discussing their description in terms of a fluctuating Z 2 gauge field. Some recent references are given to other types of spin liquid, including gapless ones.
Misguich, Gr�goire
Do Measures of Liquidity Measure Liquidity?
Liquidity plays an increasingly important role in empirical asset pricing, market efficiency, and corporate finance. Identifying high quality proxies for liquidity based on daily data only (not intraday data) would permit liquidity to be studied over relatively long timeframes and across many countries. We introduce new liquidity measures. We run horseraces of both monthly and annual liquidity measures. We compare
Ruslan Y. Goyenko
NSDL National Science Digital Library
This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba
Eichinger, John
Liquid filtration is a fundamental unit operation practiced extensively throughout the chemical process, petroleum, and allied industries. This book is a state-of-the-art review of this operation. The text reviews specific design and selection criteria, both theoretical and practical. There are many actual industrial problems given as a means of further elucidating the principles of filtration that are presented. All of
N. P. Cheremisinoff; D. S. Azbel
Dynamics of highly excited nitroaromatics.
Although the photodissociation of nitroaromatics in low excitation electronic states has been extensively studied in recent decades, little is known about the highly excited electronic states. The fragmentation dynamics of three nitroaromatics, nitrobenzene, o-nitrotoluene, and m-nitrotoluene, in highly excited states, populated by the absorption of two photons at 271 nm, are studied with time-of-flight mass spectrometry. The temporal evolutions of the highly excited states are monitored by one-photon ionization at 408 nm. The transients of parent and fragment ions exhibit two ultrafast deactivation processes. The first process is ultrafast internal conversion from the initial excitation to Rydberg states in tens of femtoseconds. The second one is conversion from the Rydberg states to the vibrational manifold in the ground electronic states within hundreds of femtoseconds. The internal conversion process is accelerated by methyl substitution. In o-nitrotoluene, the two processes become much faster due to the hydrogen transfer from the CH(3) to the NO(2) group (ortho effect). PMID:21090786
Wang, Bingxing; Liu, Benkang; Wang, Yanqiu; Wang, Li
News CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events
NASA Astrophysics Data System (ADS)
CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events
Excitation optimization for damage detection
A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.
Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD
Autoresonant Excitation of Antiproton Plasmas
NASA Astrophysics Data System (ADS)
We will present results of the first longitudinal autoresonant excitation of a thermal antiproton plasma. We apply a swept-frequency drive field to an antiproton plasma in an anharmonic potential to resonantly control the longitudinal energy of the particles in the potential. We observe autoresonant excitation of the plasma as a macroparticle in the regime of cold, dense plasmas, while warmer, tenuous plasmas are not excited completely (as predicted by theory [1]). This technique has been used for initiating the formation of antihydrogen, as it provides a flexible method for injecting antiprotons into a positron plasma of fluctuating space-charge while minimizing the kinetic energy of the antiprotons possessed by the antiprotons just after injection. As efforts to trap and conduct spectroscopy on antihydrogen require the formation of cold antihydrogen, minimizing energy mismatches in formation is key to successful trapping. References [1] Barth, I., et al, Phys. Rev. Lett. 103, 155001 (2009)
Bertsche, William
Modeling excitable systems: Reentrant tachycardia
NASA Astrophysics Data System (ADS)
Excitable membranes are an important type of nonlinear dynamical system, and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh-Nagumo equations, and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project or as a senior thesis or honors project and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.
Lancaster, Jarrett L.; Hellen, Edward H.; Leise, Esther M.
NASA Technical Reports Server (NTRS)
Conceptual design for heat exchanger, utilizing two immiscible liquids with dissimilar specific gravities in direct contact, is more efficient mechanism of heat transfer than conventional heat exchangers with walls or membranes. Concept could be adapted for collection of heat from solar or geothermal sources.
Miller, C. G.
Autoresonant Excitation of Antiproton Plasmas
We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.
Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)
Electron impact excitation of coronene
NASA Technical Reports Server (NTRS)
A preliminary study of the electron-impact excitation of thermally evaporated coronene at 550 C was carried out using electron-energy-loss spectroscopy. Measurements of the energy-loss spectra of coronene at high (100 eV) and low (5-20 eV) impact energies are presented. One of the high-energy spectra was converted to an apparent generalized oscillator strength spectrum and compared to the photoabsorption spectrum of coronene. Observations concerning vibrational excitation of coronene by electron impact are also presented and discussed.
Khakoo, M. A.; Ratliff, J. M.; Trajmar, S.
Nuclear excitation by positron annihilation
Experimental and theoretical studies of the excitation of low-lying states of the nuclei /sup 113//sup ,//sup 115/In, /sup 111/Cd, /sup 103/Rh, /sup 107//sup ,//sup 109/Ag, /sup 176/Lu, and /sup 197/Au by the annihilation of positrons with atomic shell electrons are reviewed. Neutron emission from the /sup 9/ Be nucleus due to nonradiative annihilation of positrons is considered. A new phenomenon: excitation of the daughter nucleus by positron annihilation in ..beta../sup +/ decay: is discussed.
Vishnevskii, I.N.; Zheltonozhskii, V.A.; Kolomiets, V.M.
Excited hadronic matter in the temperature interval T = 100--200 MeV is not an ideal pion gas, but rather a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the quasipion'' comes to the boundary of the system. We show that effects can provide and explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions. 31 refs., 13 figs.
Shuryak, E.V.
Fluorescence Excitation of Single Molecules.
National Technical Information Service (NTIS)
A few years ago, many people would have deemed the optical observation of single molecules nearly impossible. Yet, new experiments at room and at liquid helium temperatures have started to remove this psychological barrier. Several applications to trace d...
M. Orrit J. Bernard
A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.
Ekechukwu, Amy A. (Augusta, GA)
Spin-exchange dynamical structure factor of the S=1/2 Heisenberg chain.
We determine the spin-exchange dynamical structure factor of the Heisenberg spin chain, as is measured by indirect resonant inelastic x-ray scattering (RIXS). We find that two-spin RIXS excitations nearly entirely fractionalize into two-spinon states. These share the same continuum lower bound as single-spin neutron scattering excitations, even if the relevant final states belong to orthogonal symmetry sectors. The RIXS spectral weight is mainly carried by higher-energy excitations, and is beyond the reach of the low-energy effective theories of Luttinger liquid type. PMID:21568610
Klauser, Antoine; Mossel, Jorn; Caux, Jean-S�bastien; van den Brink, Jeroen
Raman excitation profile of nitrobenzene: prospect of Raman lidar detection
NASA Astrophysics Data System (ADS)
The absolute values of the Raman scattering cross-section of the 1347 cm-1 NO2 symmetric stretch mode of nitrobenzene vapor were measured at some discrete excitation wavelengths in the range 240 nm to 420 nm. An analytical expression for their wavelength dependence was obtained from the numerical `best fit' of the data to Albrecht `A' term. The Raman excitation profile, thus created, exhibits a strong resonance effect, attributed to the charge-transfer state in C6H5NO2 corresponding to the absorption peak at 240 nm. At near resonance excitation (250 nm) the Raman cross-section was found to be more than two orders of magnitude higher than that expected at the same wavelength from (lambda) -4 dependence. Although the excitation profile remained the same, the vapor phase cross-section values were almost an order of magnitude lower than those measured in liquid phase. The implication of resonance enhancement on the Raman lidar detection of NB vapor was analyzed for a standard atmospheric model with different ozone loadings using LOWTRAN7 computer code.
Ahmad, Sheikh R.; Foster, V. G.
NASA Technical Reports Server (NTRS)
Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.
Elliott, D. G.
Capacitive Excitation for Induction Generators
Up to the present, applications of induction generators have been limited, mainly because they must be paralleled with an existing synchronous system to determine their frequency and voltage and to obtain their necessary excitation. The tests described in this paper show that an induction machine may be operated as an independent or isolated generator at a predetermined voltage and frequency,
E. D. Bassett; F. M. Potter
Magnetically induced pulser laser excitation
A novel excitation scheme has been developed for excimer discharge lasers. The technique uses pulse transformer technology to induce a fast, high voltage pulse directly onto a ground potential laser electrode resulting in the breakdown of the laser gas mix. Saturation of the pulse transformer core inductance then permits efficient energy transfer from the main energy storage circuit into the
R. S. Taylor; K. E. Leopold
Dissociation of Highly Excited Molecules
NASA Astrophysics Data System (ADS)
A survey of the spectroscopy and dynamics of the dissociation of highly excited molecules is presented with emphasis on superexcited molecules by electron- and photon-impact.(See review articles: a) Y. Hatano, The Physics of Electronic and Atomic Collisions, eds., L. J. Dube et al., AIP Press, New York (1995) pp.67-88; b) N.Kouchi et al., J. Phys. B, 30, 2319 (1997); c) Y. Hatano, Dynamics of Excited Molecules, ed., K. Kuchitsu, Elsevier, Amsterdam (1994) Chapter 6.) Topics will include newly developed experimental methods covering two-dimensional spectroscopy of photodissociation(M. Ukai et al., Phys. Rev. Lett., 74, 239 (1995).) (S. Machida et al., J. Phys. Chem. A. 101, 656 (1997).) (A. Ehresmann et al., J. Phys. B, 29, 3629 (1996).), and coincident electron-energy-loss spectroscopy of the dissociation dynamics of highly excited molecules.(T. Odagiri et al., J. Phys. B, 28, L465 (1995).)(T. Odagiri et al., J. Phys. B, 29, 1829 (1996).) The measurement of absolute photoionization quantum yields will also be discussed.(K. Kameta et al., J. Chem. Phys., 99, 2487 (1993).) Comparative studies of electron- and photon-impact dissociative excitation of molecules will be summarized. The molecules studied are H_2, N_2, O_2, CO, CO_2, N_2O, hydrocarbons, and some Si-containing compounds.
Hatano, Yoshihiko
Communicating the Excitement of Science
In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).
Michael Turner
Pseudorandom selective excitation in NMR
NASA Astrophysics Data System (ADS)
In this work, average Hamiltonian theory is used to study selective excitation under a series of small flip-angle ?-pulses ? ? {?}/{3} applied either periodically [corresponding to the DANTE pulse sequence] or aperiodically to a spin-1/2 system. First, an average Hamiltonian description of the DANTE pulse sequence is developed that is valid for frequencies either at or very far from integer multiples of {1}/{?}, where ? is the interpulse delay. For aperiodic excitation, a single resonance, ?sel, can be selectively excited if the ?-pulse phases are modulated in concert with the interpulse delays. The conditions where average Hamiltonian theory can be accurately applied to describe the dynamics under aperiodic selective pulses, which are referred to as pseudorandom-DANTE or p-DANTE sequences, are similar to those found for the DANTE sequence. Signal averaging over different p-DANTE sequences improves the apparent selectivity at ?sel by reducing the excitations at other frequencies. Experimental demonstrations of p-DANTE sequences and comparisons with the theory are presented.
Walls, Jamie D.; Coomes, Alexandra
Communicating the Excitement of Science
In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).
Michael Turner
Hydrodynamic pressure in a tank containing two liquids
A study on the dynamic response of a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response functions examined include the hydrodynamic pressure, base shear and base moments. A simple approach that can be used to estimate the fundamental natural frequency of the tank-liquid system containing two liquids is proposed. This simple approach is an extension of the method used for estimating the frequency of a tank-liquid system containing only one liquid. This study shows that the dynamic response of a tank filled with two liquids is quite different from that of an identical tank filled with only one liquid.
Tang, Yu
Hydrodynamic pressure in a tank containing two liquids
A study on the dynamic response of a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response functions examined include the hydrodynamic pressure, base shear and base moments. A simple approach that can be used to estimate the fundamental natural frequency of the tank-liquid system containing two liquids is proposed. This simple approach is an extension of the method used for estimating the frequency of a tank-liquid system containing only one liquid. This study shows that the dynamic response of a tank filled with two liquids is quite different from that of an identical tank filled with only one liquid.
Tang, Yu.
Dynamics of vibrating systems with tuned liquid column dampers and limited power supply
NASA Astrophysics Data System (ADS)
Tuned liquid column dampers are U-tubes filled with some liquid, acting as an active vibration damper in structures of engineering interest like buildings and bridges. We study the effect of a tuned liquid column damper in a vibrating system consisting of a cart which vibrates under driving by a source with limited power supply (non-ideal excitation). The effect of a liquid damper is studied in some dynamical regimes characterized by coexistence of both periodic and chaotic motion.
de Souza, S. L. T.; Caldas, I. L.; Viana, R. L.; Balthazar, J. M.; Brasil, R. M. L. R. F.
Liquid-crystalline nanoparticles: Hybrid design and mesophase structures
Summary Liquid-crystalline nanoparticles represent an exciting class of new materials for a variety of potential applications. By combining supramolecular ordering with the fluid properties of the liquid-crystalline state, these materials offer the possibility to organise nanoparticles into addressable 2-D and 3-D arrangements exhibiting high processability and self-healing properties. Herein, we review the developments in the field of discrete thermotropic liquid-crystalline nanoparticle hybrids, with special emphasis on the relationship between the nanoparticle morphology and the nature of the organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed.
Greget, Romain; Dominguez, Cristina; Nagy, Zsuzsanna T; Guillon, Daniel; Gallani, Jean-Louis
Liquid jet waveguide for Raman spectroscopy
NASA Astrophysics Data System (ADS)
An optofluidic jet waveguide for Raman spectroscopy is reported. In this device a micro-channel is used to produce a high speed liquid stream acting at the same time, as the solution to analyse and as an optical waveguide. The liquid waveguide, exploiting total internal reflection, is able to effectively collect the Raman signal produced by the chemical compound under analysis opportunely excited by means of a laser source. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the Raman signal towards the detection system. The waveguiding nature of a liquid jet enables high Raman signal collection and the device configuration allows strong reduction of the background as no confining walls are used to contain the solution to analyse. The performances of the system have been successfully tested on isopropyl alcohol in water solutions showing a detection limit for this chemical compound of 0.8+/-0.1%.
Persichetti, Gianluca; Testa, Genni; Bernini, Romeo
Lasing effect in blue phase liquid crystal
NASA Astrophysics Data System (ADS)
We report on the investigation of random lasing in blue phase liquid crystals. Multiple scattering and interference effects arising from disordered platelet texture as well as index mismatch between polymer and mesogen contribute the optical feedbacks towards laser action. In pure blue phase liquid crystals, the random laser can be switched between the coherent and incoherent types by executing distinct heating/cooling cycles; and, the randomness of lasing wavelengths can be determined by the platelet size, which can be set by controlling the cooling rate. After the blue phase liquid crystals are polymer-stabilized, coherent random lasing may occur in both the blue phase with an extended temperature interval and the isotropic liquid state; also, the selected modes are constant from one pulse to another. Additionally, if the laser dye is sensitive to temperature, the excitation threshold and the emission spectrum could be altered via thermal control.
Lin, Tsung-Hsien; Chen, Chun-Wei; Jau, Hung-Chang; Lee, Chun-Hong; Wang, Chun-Ta; Wu, Chih-Wei; Huang, Huai-Ping; Khoo, I. C.
Vibrational energy relaxation in liquids
NASA Astrophysics Data System (ADS)
The de-excitation of the vibrational population of small molecules in the liquid state is considered. Experimental techniques applicable to the measurement of relaxation times in dense phases are first described. Theoretical approaches are subsequently developed with special emphasis on the relationship between ab-initio quantum methods and binary interaction models. Finally, a selection of experimental results is analysed in the light of these theories. Special attention is given to the dependence of the relaxation time on experimental parameters such as density, temperature or the concentration of a mixture. The behaviour of the relaxation time across the liquid/solid phase transition is also treated. La d�sexcitation vibrationnelle de petites mol�cules est �tudi�e en phase liquide. Les techniques exp�rimentales utilisables pour mesurer les temps de relaxation en phase dense sont d'abord d�crites. Les approches th�oriques sont ensuite d�velopp�es en montrant en particulier les liens entre les deux principales : l'approche quantique ab-initio et les mod�les d'interaction binaire. Un choix de r�sultats exp�rimentaux est finalement analys� � la lumi�re de ces th�ories. Les d�pendances des temps de relaxation envers les param�tres exp�rimentaux, comme la densit�, la temp�rature ou la concentration d'un m�lange, sont sp�cialement �tudi�es. Le comportement de la relaxation � la transition liquide/solide est aussi abord�.
Chesnoy, J.; Gale, G. M.
NASA Technical Reports Server (NTRS)
A device for mixing liquid nitrogen and liquid oxygen to form liquid air. The mixing device consists of a tube for transferring liquid oxygen positioned within a tube for transferring liquid nitrogen. Supply vessels for liquid oxygen and liquid nitrogen are equally pressurized and connected to the appropriate tubes. Liquid oxygen and nitrogen flow from the supply vessels through the respective tubes and are mixed to form liquid air upon exiting the outlets of the tube. The resulting liquid air is transferred to a holding vessel.
Martin, Robert B. (Inventor)
A Method of Exciting Vibrations in Plates, Membranes, etc., Based on the Bernoulli Principle
It is known that a plate placed close to a flanged orifice from which a stream of air or liquid is issuing is attracted towards the orifice. If the plate be mounted as a diaphragm it can be excited to strong vibration by a suitable blast, and a loud sound is produced with high efficiency.
Kerr Grant
Excitations of Amorphous Solid Helium
NASA Astrophysics Data System (ADS)
We present neutron scattering measurements of the dynamic structure factor, S(Q,?), of amorphous solid helium confined in 47 \\ptilde ore diameter MCM-41 at pressure 48.6 bar. At low temperature, T = 0.05 K, we observe S(Q,?) of the confined quantum amorphous solid plus the bulk polycrystalline solid between the MCM-41 powder grains. No liquid-like phonon-roton modes, other sharply defined modes at low energy (?< 1.0 meV) or modes unique to a quantum amorphous solid that might suggest superflow are observed. Rather the S(Q,?) of confined amorphous and bulk polycrystalline solid appear to be very similar. At higher temperature (T> 1 K), the amorphous solid in the MCM-41 pores melts to a liquid which has a broad S(Q,?) peaked near ?� 0 characteristic of normal liquid ^4He under pressure. Expressions for the S(Q,?) of amorphous and polycrystalline solid helium are presented and compared. In previous measurements of liquid ^4He confined in MCM-41 at lower pressure the intensity in the liquid roton mode decreases with increasing pressure until the roton vanishes at the solidification pressure (38 bars), consistent with no roton in the solid observed here
Bossy, Jacques; Ollivier, Jacques; Schober, Helmut; Glyde, Henry R.
Pair Excitations and Vertex Corrections in Fermi Fluids
Based on an equations�of�motion approach for time�dependent pair correlations in strongly interacting Fermi liquids, we have developed a theory for describing the excitation spectrum of\\u000a these systems. Compared to the known �correlated� random�phase approximation (CRPA), our approach has the following properties:\\u000a (i)�The CRPA is reproduced when pair fluctuations are neglected. (ii)�The first two energy�weighted sumrules are fulfilled\\u000a implying a correct
Helga M. B�hm; Eckhard Krotscheck; Martin Panholzer
Excitations in a four-leg antiferromagnetic Heisenberg spin tube
Inelastic neutron scattering is used to investigate magnetic excitations in the quasi-one-dimensional quantum spin-liquid system Cu$_2$Cl$_{4}\\cdot$ D$_8$C$_4$SO$_2$. Contrary to previously conjectured models that relied on bond-alternating nearest neighbor interactions in the spin chains, the dominant interactions are actually next-nearest-neighbor in-chain antiferromagnetic couplings. The appropriate Heisenberg Hamiltonian is equivalent to that of a $S=1/2$ 4-leg spin-tube with almost perfect one dimensionality and no bond alternation. A partial geometric frustration of rung interactions induces a small incommensurability of short-range spin correlations.
Garlea, Vasile O [ORNL; Zheludev, Andrey I [ORNL; Regnault, L.-P. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Boehm, Martin [Institut Laue-Langevin (ILL); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Meissner, Michael [Hahn-Meitner Institut, Berlin, Germany
Excitations in a Four-Leg Antiferromagnetic Heisenberg Spin Tube
Inelastic neutron scattering is used to investigate magnetic excitations in the quasi-one-dimensional quantum spin-liquid system Cu2Cl4 D8C4SO2. Contrary to previously conjectured models that relied on bond-alternating nearest-neighbor interactions in the spin chains, the dominant interactions are actually next-nearest-neighbor in-chain antiferromagnetic couplings. The appropriate Heisenberg Hamiltonian is equivalent to that of a S 1=2 4-leg spin-tube with almost perfect one dimensionality and no bond alternation. A partial geometric frustration of rung interactions induces a small incommensurability of short-range spin correlations.
Garlea, Vasile O [ORNL; Zheludev, Andrey I [ORNL; Regnault, L.-P. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Boehm, Martin [Institut Laue-Langevin (ILL); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Meissner, Michael [Hahn-Meitner Institut, Berlin, Germany; Fernandez-Baca, Jaime A [ORNL
NSDL National Science Digital Library
In this density activity, students determine the relative densities of five liquids and layer them atop one another in a straw. Directions for conducting the activity are included in addition to lists of the science process skills, complex reasoning strategies, and National Science Education Standards that relate to it. A brief explanation of the activity's science content and an assessment idea are also provided. This activity is part of a set called Whelmers that were designed to inspire students to think about science concepts.
Mid-continent Research for Education and Learning (McREL); Jacobs, Steve
A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.
Ekechukwu, A.A.
Superheating water by CW excitation of gold nanodots.
A temperature-dependent photoluminescent thin film of Al(0.94)Ga(0.06)N doped with Er(3+) is used to measure the temperature of lithographically prepared gold nanodots. The gold nanodots and thin film are excited simultaneously with a continuous wave (CW) Nd:YAG 532 nm laser. The gold nanodot is submersed under water, and the dot is subsequently heated. The water immediately surrounding the nanodot is superheated beyond the boiling point up to the spinodal decomposition temperature at 594 � 17 K. The spinodal decomposition has been confirmed with the observation of critical opalescence. We characterize the laser scattering that occurs in unison with spinodal decomposition due to an increased coherence length associated with the liquid-liquid transition. PMID:22313363
Carlson, Michael T; Green, Andrew J; Richardson, Hugh H
Raman excitation profile of diphenylamine
NASA Astrophysics Data System (ADS)
Vibrational analyses have been done on the basis of Raman and FTIR spectra of diphenylamine (DPA) and contributions of the two rings to different normal modes of vibration have been discussed. From the analyses of Raman excitation profiles (REPs) of several vibrational modes, useful information about the geometries of the molecule in different excited states have been obtained. Also vibronic coupling has been found to be important in the case of some Raman bands. Besides an interesting Molecular Orbital (MO) calculation, exploring the structure of DPA in the allowed singlet electronic state ( 1La) , has been presented. Moreover, possible orientations of the two rings with respect to the amine nitrogen atom in the ground and in the 1La states have been discussed.
Sett, P.; De, A. K.; Chattopadhyay, S.; Mallick, P. K.
Excitation spectrum of a supersolid.
Conclusive experimental evidence of a supersolid phase in any known condensed matter system is presently lacking. On the other hand, a supersolid phase has been recently predicted for a system of spinless bosons in continuous space, interacting via a broad class of soft-core, repulsive potentials. Such an interaction can be engineered in assemblies of ultracold atoms, providing a well-defined pathway to the unambiguous observation of this fascinating phase of matter. In this Letter, we study by first principles computer simulations the elementary excitation spectrum of the supersolid, and show that it features two distinct modes, namely, a solidlike phonon and a softer collective excitation, related to broken translation and gauge symmetry, respectively. PMID:22680879
Saccani, S; Moroni, S; Boninsegni, M
NASA Astrophysics Data System (ADS)
The structure of the neutron-rich N=20 nucleus P35 has been investigated through nucleon transfer experiments using the 208Pb(36,X?) reaction at 230 MeV. The level structure, of mainly 1?? excitations in P35, has been significantly expanded. The measurements are compared with shell model calculations. Experimental branching ratio limits are reported for predicted transitions to the 2?? bandheads in P35 and Si34.
Wiedeking, M.; Rodriguez-Vieitez, E.; Fallon, P.; Carpenter, M. P.; Clark, R. M.; Cline, D.; Cromaz, M.; Descovich, M.; Janssens, R. V. F.; Lee, I.-Y.; Deleplanque, M.-A.; Macchiavelli, A. O.; Stephens, F. S.; Teng, R.; Wang, X.; Ward, D.; Wu, C. Y.; Zhu, S.; Otsuka, T.; Utsuno, Y.; Volya, A.
Magnetic excitations in vanadium spinels
We study magnetic excitations in vanadium spinel oxides AV2O4 (A=Zn,Mg,Cd) using two models: the first one is a superexchange model for vanadium S=1 spins and the second one includes, in addition, spin-orbit coupling and crystal anisotropy. We show that the experimentally observed magnetic ordering can be obtained in both models; however, the orbital ordering is different with and without spin-orbit
N. B. Perkins; O. Sikora
Chiral multiplets of excited mesons
It is shown that experimental meson states with spins J=0,1,2,3 in the energy range 1.9�2.4 GeV obtained in a recent partial wave analysis of proton�antiproton annihilation at LEAR remarkably confirm all predictions of chiral symmetry restoration. Classification of excited q?q mesons according to the representations of chiral U(2)L�U(2)R group is performed. There are two important predictions of chiral symmetry restoration
L. Ya. Glozman
Excitation of slosh waves associated with low frequency impulsive reverse gravity acceleration of geyser initiation
NASA Technical Reports Server (NTRS)
The objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid and vapor within a tank in reduced gravity to enable liquid outflow or vapor venting. The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank prior to main engine restart poses a microgravity fluid behavior problem. The purpose of the present study is to investigate the stability of the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. In this study slosh wave excitation induced by the resettling flow field activated by 0.1 Hz low frequency, impulsive reverse gravity acceleration, during reorientation with the initiation of geyser for liquid fill levels of 30, 50, 65, 70 and 80 percent, have been studied. Characteristics of slosh waves with various frequencies excited are discussed. Slosh wave excitation shift the fluid mass distribution in the container which impose time dependent variations in spacecraft moment of inertia. This information is important for the spacecraft control during the course of liquid reorientation.
Hung, R. J.; Shyu, K. L.
Self-excited multifractal dynamics
NASA Astrophysics Data System (ADS)
We introduce the self-excited multifractal (SEMF) model, defined such that the amplitudes of the increments of the process are expressed as exponentials of a long memory of past increments. The principal novel feature of the model lies in the self-excitation mechanism combined with exponential nonlinearity, i.e. the explicit dependence of future values of the process on past ones. The self-excitation captures the microscopic origin of the emergent endogenous self-organization properties, such as the energy cascade in turbulent flows, the triggering of aftershocks by previous earthquakes and the "reflexive" interactions of financial markets. The SEMF process has all the standard stylized facts found in financial time series, which are robust to the specification of the parameters and the shape of the memory kernel: multifractality, heavy tails of the distribution of increments with intermediate asymptotics, zero correlation of the signed increments and long-range correlation of the squared increments, the asymmetry (called "leverage" effect) of the correlation between increments and absolute value of the increments and statistical asymmetry under time reversal.
Filimonov, V.; Sornette, D.
High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host
A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.
Comaskey, Brian J. (Walnut Creek, CA); Ault, Earl R. (Livermore, CA); Kuklo, Thomas C. (Oakdale, CA)
Blade Vibration Due to Different Flow Excitation.
National Technical Information Service (NTIS)
Results of experiments carried out at various excitation conditions, variations in geometry, and especially in diffuser flow conditions are presented. The analysis includes the study of blade resonance excitation, blade flutter, vibrations due to surge, a...
U. Haupt
Reactions of Electronically Excited Oxygen Molecules.
National Technical Information Service (NTIS)
A method of obtaining measurable concentrations of excited oxygen for kinetic studies has been developed, and a number of reactions of these excited molecules are described. Evidence is presented for simultaneous electronic transitions in a weakly bound c...
L. W. Bader E. A. Ogryzlo
Rocking response of tanks containing two liquids
A study on the dynamic response of upright circular cylindrical liquid-storage tanks containing two different liquids under a rocking base motion with an arbitrary temporal variation is presented. Only rigid tanks were studied. The response quantities examined include the hydrodynamic pressure, sloshing wave height and the associated frequencies, base shear and moments. Each of these response quantities is expressed as the sum of the so-called impulsive component and convective component. Unlike the case of tanks containing one liquid, in which the response is controlled by one parameter, height-to-radius ratio, the response of tanks containing two different liquids are controlled by three parameters: height-to-radius ratio, and mass density ratio and height ratio of the two liquids. The interrelationship of the responses of the tank-liquid system to rocking and lateral base excitations is established by examining numerical results extensively. The study shows that some of the response quantities for tank-liquid system under a rocking base motion can be determined from the available data for the response of an identical tank under a horizontal base motion. Base rocking motion can occur in a ground-supported tank or in an elevated tank under earthquake motions.
Tang, Y. [Argonne National Lab., IL (United States). Reactor Engineering Div.
Excitations of amorphous solid helium
NASA Astrophysics Data System (ADS)
We present neutron scattering measurements of the dynamic structure factor S(Q,?) of amorphous solid helium confined in 47-� pore diameter MCM-41 at pressure 48.6 bars. At low temperature T=0.05 K, we observe S(Q,?) of the confined quantum amorphous solid plus the bulk polycrystalline solid between the MCM-41 powder grains. No liquidlike phonon-roton modes, other sharply defined modes at low energy (?< 1.0 meV), or modes unique to a quantum amorphous solid that might suggest superflow are observed. Rather, the S(Q,?) of confined amorphous and bulk polycrystalline solid appear to be very similar. At higher temperature (T> 1 K), the amorphous solid in the MCM-41 pores melts to a liquid which has a broad S(Q,?) peaked near w?0, characteristic of normal liquid 4He under pressure. Expressions for the S(Q,?) of amorphous and polycrystalline solid helium are presented and compared. In previous measurements of liquid 4He confined in MCM-41 at lower pressure, the intensity in the liquid roton mode decreases with increasing pressure until the roton vanishes at the solidification pressure (38 bars), consistent with no roton in the solid observed here.
Bossy, Jacques; Ollivier, Jacques; Schober, Helmut; Glyde, H. R.
The more liquid a firm's assets, the greater their value in a short-notice liquidation. It is generally thought that a firm should find it easier to raise external finance against more liquid assets. This paper focuses on the dark side of liquidity: greater asset liquidity reduces the firm's ability to commit to a specific course of action. As a result,
Stewart C. Myers; Raghuram G. Rajan
Two-photon excitation of aluminium phthalocyanines
A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)
Meshalkin, Yu P; Alfimov, E E; Makukha, V K [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Vasil'ev, N E; Denisov, A N; Ogirenko, A P [Siberian Laser Medicine Centre, Novosibirsk (Russian Federation)
Steam turbine generator excitation system modernization
Many power plants built 20-30 years ago are facing problems associated with the excitation system used for controlling generator output voltage. After years of reliable operation, generation is experiencing increased down time due to maintenance associated with the existing excitation equipment. Reliability of the excitation system has become an issue, especially where many of these generation plants may be critical
Richard C. Schaefer
Collective Excitations in the Theory of Superconductivity
The complex dielectric constant of a superconductor and the Meissner effect are derived in a manner which is gauge invariant, from the theory of superconductivity due to Bardeen, Cooper, and Schrieffer. The collective excitations are important in maintaining gauge invariance; the longitudinal collective excitations ensure that a static vector potential produces no longitudinal current and the transverse collective excitations contribute
G. Rickayzen
Determination of bisphenol A (BPA) in the presence of phenol by first-derivative fluorescence following micro liquid�liquid extraction (MLLE)
Bisphenol A (BPA) in the presence of phenol is determined using a method based on first-derivative spectrofluorimetry. The proposed method involves a micro liquid�liquid extraction of sodium chloride saturated water samples with diethyl ether followed by direct fluorimetric analysis of extracts. The excitation spectra of both compounds in diethyl ether are recorded between 200 and 290 nm, with the emission
M. del Olmo; A. Zafra; A. B. Jurado; J. L. Vilchez
Cosmology with liquid mirror telescopes
NASA Astrophysics Data System (ADS)
Liquid mirrors provide an exciting means to obtain large optical telescopes for substantially lower costs than conventional technologies. The liquid mirror concept has been demonstrated in the lab with the construction of a diffraction limited 1.5 m mirror. The mirror surface, using liquid mercury, forms a perfect parabolic shape when the mirror cell is rotated at a uniform velocity. A liquid mirror must be able to support a heavy mercury load with minimal flexure and have a fundamental resonant frequency that is as high as possible, to suppress the amplitude of surface waves caused by small vibrations transmitted to the mirror. To minimize the transmission of vibrations to the liquid surface, the entire mirror rests on an air bearing. This necessitates the mirror cell being lightweight, due to the limited load capabilities of the air bearing. The mirror components must also have physical characteristics which minimize the effects of thermal expansion with ambient temperature fluctuations in the observatory. In addition, the 2.7 m mirror construction is designed so that the techniques used may be readily extended to the construction of large mirrors. To attain the goals of a lightweight, rigid mirror, a composite laminant construction was used. The mirror consists of a foam core cut to the desired parabolic shape, with an accuracy of a few mm. An aluminum hub serves as an anchor for the foam and skin, and allows precise centering of the mirror on the air bearing and drive system. Several plys of Kevlar, covered in an epoxy matrix, are then applied to the foam. A final layer of pure epoxy is formed by spin casting. This final layer is parabolic to within a fraction of a mm. An aluminum ring bonded to the circumference of the mirror retains the mercury, and incorporates stainless-steel hard-points for the attachment of balance weights.
Hogg, David W.; Gibson, Brad K.; Hickson, Paul
Ultrafast Conversions Between Hydrogen Bonded Structures in Liquid Water Observed by Femtosecond X-Ray Spectroscopy.
National Technical Information Service (NTIS)
We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray ...
A. M. Lindenberg H. Wen N. Huse R. W. Schoenlein
Diffusion of photoexcited azo dye in a liquid-crystal host.
Dynamic holograms are created and studied in a D2 azo-dye-doped nematic liquid crystal. The dependence of diffraction on the excitation and probe polarizations is observed. The efficiency of excitation and the corresponding relaxation time depend also on the period and orientation of the light-interference pattern with respect to the initial molecular orientation. The excitation and diffusion of dye molecules are suggested to be the origin of these phenomena. PMID:18087323
Saad, B; Denariez-Roberge, M M; Galstyan, T V
Liquid-liquid-solid transition in viscoelastic liquids
Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle.
Zubelewicz, Aleksander
Liquid-liquid-solid transition in viscoelastic liquids.
Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528
Zubelewicz, Aleksander
Pair Excitations and Vertex Corrections in Fermi Fluids
NASA Astrophysics Data System (ADS)
Based on an equations-of-motion approach for time-dependent pair correlations in strongly interacting Fermi liquids, we have developed a theory for describing the excitation spectrum of these systems. Compared to the known �correlated� random-phase approximation (CRPA), our approach has the following properties: (i) The CRPA is reproduced when pair fluctuations are neglected. (ii) The first two energy-weighted sumrules are fulfilled implying a correct static structure. (iii) No ad-hoc assumptions for the effective mass are needed to reproduce the experimental dispersion of the zero sound mode in 3He. (iv) The density response function displays a novel form, arising from vertex corrections in the proper polarisation. Our theory is presented here with special emphasis on this latter point. We have also extended the approach to the single particle self-energy and included pair fluctuations in the same way. The theory provides a diagrammatic superset of the familiar GW approximation. It aims at a consistent calculation of single particle excitations with an accuracy that has previously only been achieved for impurities in Bose liquids.
B�hm, Helga M.; Krotscheck, Eckhard; Panholzer, Martin
National Technical Information Service (NTIS)
The patent application discloses a method and an apparatus for fermenting liquids. Liquids are fermented by controlling flow patterns within the liquid so as to retain fermentation culture medium in a fermenting chamber while at the same time removing fer...
E. Wick
NSDL National Science Digital Library
The Liquid Crystal Institute website provides information on the interdisciplinary research and development of liquid crystal optoelectronic materials, technology, and consumer products. It provides basic information on what liquid crystals are as well as how they are made and used.
Institute, Liquid C.
Liquid Crystal Polyester Thermosets.
National Technical Information Service (NTIS)
The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materi...
B. C. Benicewicz A. E. Hoyt
Liquid crystal polyester thermosets.
National Technical Information Service (NTIS)
The present invention relates to the field of curable liquid crystal polyester monomers and to thermoset liquid crystalline polyester compositions prepared therefrom. It is an object of this invention to provide curable liquid crystalline polyester materi...
B. C. Benicewicz A. E. Hoyt
... attention. If the cut is minor, a liquid bandage (liquid adhesive) can be used on the cut ... wound and help stop bleeding. Using a liquid bandage is quick and painless to apply. Skin adhesives, ...
ERIC Educational Resources Information Center
Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)
Marroum, Renata-Maria
Liquid-Liquid Extraction of Cobalt.
National Technical Information Service (NTIS)
This invention relates to liquid-liquid extraction of cobalt from leach solutions and, more particularly, to extraction of cobalt from raffinate remaining after extraction of nickel from ammonium sulfate leach solutions containing both nickel and cobalt. ...
D. C. Thompson
Turbulent swirling jets with excitation
NASA Technical Reports Server (NTRS)
An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.
Taghavi, Rahmat; Farokhi, Saeed
Collective excitations in the continuum
Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.
Dussel, G. G. [Departamento de Fisica, FCEyN-UBA, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Betan, R. Id [Departamento de Quimica y Fisica, FCEIA (UNR)-Instituto de Fisica Rosario, IFIR (CONICET), 2000 Rosario (Argentina); Liotta, R. J. [KTH, Alba Nova University Center, S-10691 Stockholm (Sweden); Vertse, T. [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen (Hungary); Faculty of Informatics, University of Debrecen, H-4010 Debrecen (Hungary)
High Frequency Chandler Wobble Excitation
NASA Astrophysics Data System (ADS)
Variations of Earth rotation on sub-daily to secular timescales are caused by mass redistributions in the Earth system as a consequence of geophysical processes and gravitational influences. Forced oscillations of polar motion are superposed by free oscillations of the Earth, i.e. the Chandler wobble and the free core nutation. In order to study the interactions between externally induced polar motion and the Earth's free oscillations, a non-linear gyroscopic model has been developed. In most of the former investigations on polar motion, the Chandler wobble is introduced as a damped oscillation with predetermined frequency and amplitude. However, as the effect of rotational deformation is a backcoupling mechanism of polar motion on the Earth's rotational dynamics, both period and amplitude of the Chandler wobble are time-dependent when regarding additional excitations from, e.g., atmospheric or oceanic mass redistributions. The gyroscopic model is free of any explicit information concerning amplitude, phase, and period of free oscillations. The characteristics of the Earth's free oscillation is reproduced by the model from rheological and geometrical parameters and rotational deformation is taken into account. This enables to study the time variable Chandler oscillation when the gyro is forced with atmospheric and oceanic angular momentum from the global atmospheric ECHAM3-T21 general circulation model together with the ocean model for circulation and tides OMCT driven by ECHAM including surface pressure. Besides, mass redistributions in the Earth's body due to gravitational and loading deformations are regarded and external torques exerted by Moon and Sun are considered. The numerical results of the gyro are significantly related with the geodetically observed time series of polar motion published by the IERS. It is shown that the consistent excitation is capable to counteract the damping and thus to maintain the Chandler amplitude. Spectral analyses of the ECHAM and OMCT forcing fields give no hint for increased excitation power in the Chandler band. Thus it is assumed, that continuous high frequency excitation due to stochastic weather phenomena is responsible for the perpetuation of the Chandler wobble.
Seitz, F.; Stuck, J.; Thomas, M.
Yields of excited states of solutes in irradiated benzene and cyclohexane
The yields of lowest excited singlet states of diphenyloxazole and p-terphenyl in benzene and of diphenyloxazole, p-terphenyl, and biphenyl in cyclohexane have been measured for excitation by using /sup 85/Kr ..beta.. particles. The dependence of the yield on solute concentration for benzene solutions is shown to be accurately represented by a Stern-Volmer function from 5 x 10/sup -4/ to 10/sup -2/ M and to extrapolate at infinite solute concentration to the yield of excited singlet states of neat liquid benzene. The presence of oxygen in the solution does not affect the extrapolation. The absolute efficiencies of energy transfer from irradiated benzene to the solutes are in good agreement with previous measurements made by using optical excitation below the ionization threshold. These results provide additional confirmation that the mechanism of formation of excited solute states in fast-electron-irradiated benzene does not significantly involve electron or hole capture by the solute. They also demonstrate that the inhomogeneity of energy deposition does not affect the ratio of probabilities of the decay of excited benzene by photon emission to its decay by nonradiative energy transfer to the solute. For cyclohexane solutions, it is confirmed that the yields of excited solute states are lower than in benzene solutions at comparable concentration, but larger than would be expected were the same nonionic mechanism to apply as it does in benzene. The consequences of these conclusions are discussed.
Choi, H.T.; Hirayama, F.; Lipsky, S.
Collective excitations of charged dust grains in dusty plasma lattices
NASA Astrophysics Data System (ADS)
Dusty Plasmas (or Complex Plasmas) are large ensembles of interacting particles, consisting of electrons, ions and massive, heavily charged, micron-sized dust particulates. The presence of the latter modifies the plasma properties substantially and allows for new charged matter configurations, including liquid-like and solid (quasi-crystalline) states (Debye crystals). One- dimensional (1d) dust crystals are formed in discharge experiments, where the electrode sheath electric fields and electrostatic interactions constitute a highly nonlinear environment. The nonlinear aspects of horizontal (longitudinal, acoustic mode) as well as vertical (transverse, optical mode) motion of charged dust grains in a (1d) dust crystal are discussed. Different types of localized excitations, predicted by nonlinear wave theories, are reviewed and conditions for their occurrence (and characteristics) in DP crystals are discussed, in a continuum approximation. Dust crystals are shown to support nonlinear kink-shaped supersonic solitary excitations, related to longitudinal dust grain displacement, as well as modulated envelope localized modes associated with either longitudinal or transverse oscillations. Furthermore, the possibility for highly localized discrete breather-type excitations to occur is investigated, for first principles. The relation to known results on atomic chains and on strongly- coupled dust layers in gas discharge plasma experiments is discussed.
Kourakis, Ioannis
Spin liquid regimes at nonzero temperature in quantum spin ice
NASA Astrophysics Data System (ADS)
Quantum spin liquids are highly entangled ground states of quantum systems with an emergent gauge structure, fractionalized spinon excitations, and other unusual properties. While these features clearly distinguish quantum spin liquids from conventional, mean-field-like states at zero temperature (T), their status at T>0 is less clear. Strictly speaking, it is known that most quantum spin liquids lose their identity at nonzero temperature, being then adiabatically transformable into a trivial paramagnet. This is the case for the U(1) quantum spin liquid states recently proposed to occur in the quantum spin ice pyrochlores. Here we propose, however, that in practical terms, the latter quantum spin liquids can be regarded as phases distinct from the high-temperature paramagnet. Through a combination of gauge mean-field theory calculations and physical reasoning, we argue that these systems sustain both quantum spin liquid and thermal spin liquid phases, dominated by quantum fluctuations and entropy, respectively. These phases are separated by a first-order �thermal confinement� transition such that, for temperatures below the transition, spinons and emergent photons are coherently propagating excitations, and above it the dynamics is classical. Even for parameters for which the ground state is magnetically ordered and not a quantum spin liquid, this strong first-order transition occurs, preempting conventional Landau-type criticality. We argue that this picture explains the anomalously low-temperature phase transition observed in the quantum spin ice material Yb2Ti2O7.
Savary, Lucile; Balents, Leon
Plasma-liquid system with rotational gliding arc with liquid electrode
NASA Astrophysics Data System (ADS)
Atmospheric pressure plasmas can be created by various types of discharges: transverse arc; discharge in gas channel with liquid wall and others. But most of them aren't sufficiently stable. Stabilization of discharge in the high pressure powerful plasmatron is attained by vortex flow of gas. In the low-powered high pressure discharges the reverse vortex flow ``tornado'' type can be used for the space stabilization. The voltage-current characteristics of discharge at the different regimes are measured. Typical emission spectra of plasma in plasma-liquid system with rotational gliding arc were measured. The population temperatures of excited electronic, vibrational, rotational levels and the flame temperature are determined.
Nedybaliuk, Oleg; Chernyak, Valeriy; Martysh, Eugene; Belenok, Natalia; Lisitchenko, Tamara
Emergent kinetics and fractionalized charge in 1D spin-orbit coupled flatband optical lattices.
Recent ultracold atomic gas experiments implementing synthetic spin-orbit coupling allow access to flatbands that emphasize interactions. We model spin-orbit coupled fermions in a one-dimensional flatband optical lattice. We introduce an effective Luttinger-liquid theory to show that interactions generate collective excitations with emergent kinetics and fractionalized charge, analogous to properties found in the two-dimensional fractional quantum Hall regime. Observation of these excitations would provide an important platform for exploring exotic quantum states derived solely from interactions. PMID:24702335
Lin, Fei; Zhang, Chuanwei; Scarola, V W
A novel micro-machined biosensor with resonant torsional paddle for direct detection in liquid
We present a novel micro-machined biosensor based on the resonant torsional paddle with electromagnetic excitation which can work in liquid directly. The sensor designed consists of two paddles with resonant torsional mode, in which the energy loss of the resonator during the vibration is so lower that it can be suitable for bio\\/chemical detection in liquid. FEM analysis was carried
Junbo Wang; Hao Li; Xiang Li; Deyong Chen
Transient stimulated Raman scattering in liquids and evaluation of picosecond pulse duration
Observation of spontaneous and stimulated Raman emission in liquids with various Raman linewidths under short pulses excitation shows the absence of self-trapping and Brillouin stimulated scattering, and the normal behavior of unperturbed stimulated Raman emission. The transient effect in liquids with small linewidths makes possible a determination of the linewidth of the laser light, and the duration and intensity of
Traveling Through Different Liquids
NSDL National Science Digital Library
Learners observe and record what happens when they manipulate bottles containing a liquid (water or corn syrup) and one or more objects (screw, nail, paper clip). They should observe differences in how quickly the objects fall in the different liquids. This lesson builds on what learners have studied in previous lessons, Exploring Liquids and Exploring How Liquids Behave.
Janulaw, Sharon
Ionic Liquids Database- (ILThermo)
National Institute of Standards and Technology Data Gateway
SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)�� IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.
NSDL National Science Digital Library
Learners add drops of four liquids (water, alcohol, salt water, and detergent solution) to different surfaces and observe the liquids' behavior. Learners will see that liquids have characteristic properties which can be used for identification. In the related activity, " Developing Tests to Distinguish Between Similar-Looking Liquids" (see related resources), learners identify an unknown based on these properties.
Kessler, James H.; Galvan, Patricia M.
Algebraic Spin Liquid in an Exactly Solvable Spin Model.
National Technical Information Service (NTIS)
We have proposed an exactly solvable quantum spin-3/2 model on a square lattice. Its ground state is a quantum spin liquid with a half integer spin per unit cell. The fermionic excitations are gapless with a linear dispersion, while the topological vison ...
H. Yao S. Zhang S. A. Kivelson
Photonic defect modes in cholesteric liquid crystal films
We discuss the properties of photonic defect modes in cholesteric liquid crystals. Twist defects, isotropic defect layers, and combinations of both are considered. After deriving the reflection and transmission properties of the defects, we study the effect of a finite sample thickness on the defect mode�s amplitude and on the required polarization of incident light to excite the defect mode.
J. Schmidtke; W. Stille
Circular Bragg phenomenon and pulse bleeding in cholesteric liquid crystals
Examining the reflection and transmission of pulses by a half-space occupied by an axially excited cholesteric liquid crystal (CLC), we uncover the spatio�temporal anatomy of the circular Bragg phenomenon exhibited by CLCs. In particular, we show the phenomenon of pulse bleeding occurs in the Bragg regime, when the handedness of the incident light coincides with the structural handedness of the
Joseph B. Geddes III; Mark W. Meredith; Akhlesh Lakhtakia
Sloshing response in a tank containing two liquids
NASA Astrophysics Data System (ADS)
A study on the sloshing response in a tank containing two different liquids under seismic excitation is presented. Both analytical and numerical (FEM) methods are employed in the analysis. The results obtained by the two methods are in good agreement. The response quantities examined include the sloshing wave height, the natural frequencies of the sloshing motion, and the vertical displacement at the interface of the two liquids. It is shown that the maximum sloshing wave height may increase significantly, and the fundamental period of the sloshing motion is longer than that in an identical tank containing only one liquid.
Tang, Y.; Ma, D. C.; Chang, Y. W.
Bubble Generation in Liquid Hydrocarbon in Divergent Fields
NASA Astrophysics Data System (ADS)
The conduction current Ic and the photocurrent Ip were measured in hydrocarbon liquids subjected to d.c. divergent fields. Space-charge limited currents were observed in clarified ionic carrier of both polarities produced by electron attachment. The linear relation between Ip and Ic indicated that molecules were excited by injected electrons before the attachment. In liquid methane in negative point electrode, Ip and Ic were reduced by a rise in pressure, giving evidence for the existence of gaseous bubbles during discharge. However in pentane and hexane, both currents were independent of pressure. The difference is probably caused by the bubble growth rate; the rate is probably larger in liquid methane.
Arii, Kiyomitsu; Kitani, Isamu
Excited baryons in lattice QCD
NASA Astrophysics Data System (ADS)
We present the first results for the masses of positive and negative parity excited baryons calculated in lattice QCD using an O(a2)-improved gluon action and a fat-link irrelevant clover (FLIC) fermion action in which only the irrelevant operators are constructed with APE-smeared links. The results are in agreement with earlier calculations of N* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner. A correlation matrix analysis reveals two low-lying JP=1/2- states with a small mass splitting. The study of different ? interpolating fields suggests a similar splitting between the lowest two ?1/2- octet states. However, the empirical mass suppression of the ?*(1405) is not evident in these quenched QCD simulations, suggesting a potentially important role for the meson cloud of the ?*(1405) and/or a need for more exotic interpolating fields.
Melnitchouk, W.; Bilson-Thompson, S.; Bonnet, F. D.; Hedditch, J. N.; Lee, F. X.; Leinweber, D. B.; Williams, A. G.; Zanotti, J. M.; Zhang, J. B.
Supersymmetric approach to excited states.
We present here a supersymmetric (SUSY) approach for determining excitation energies within the context of a quantum Monte Carlo scheme. By using the fact that SUSY quantum mechanics gives rises to a series of isospectral Hamiltonians, we show that Monte Carlo ground-state calculations in the SUSY partners can be used to reconstruct accurately both the spectrum and states of an arbitrary Schrodinger equation. Since the ground state of each partner potential is nodeless, we avoid any "node" problem typically associated with the Monte Carlo technique. Although we provide an example of using this approach to determine the tunneling states in a double-well potential, the method is applicable to any 1D potential problem. We conclude by discussing the extension to higher dimensions. PMID:19919079
Bittner, Eric R; Maddox, Jeremy B; Kouri, Donald J
Collective excitations of supersymmetric plasma
Collective excitations of N=1 supersymmetric electromagnetic plasma are studied. Since the Keldysh-Schwinger approach is used, not only equilibrium but also nonequilibrium plasma, which is assumed to be ultrarelativistic, is under consideration. The dispersion equations of photon, photino, electron, and selectron modes are written down and the self-energies, which enter the equations, are computed in the hard loop approximation. The self-energies are discussed in the context of effective action which is also given. The photon modes and electron ones appear to be the same as in the usual ultrarelativistic plasma of electrons, positrons, and photons. The photino modes coincide with the electron ones and the selectron modes are as of a free relativistic massive particle.
Czajka, Alina [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Mrowczynski, Stanislaw [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Soltan Institute for Nuclear Studies, 00-681 Warsaw (Poland)
Coulomb excitation of ruthenium isotopes
NASA Astrophysics Data System (ADS)
The B(E2) values of the 89.4, 340.4, 575.5, 617.4 and 719.2 keV states of 99Ru and 127.2, 306.8, 422.0 and 544.9 keV states of 101Ru have been deduced by measuring the yields of gamma-rays following Coulomb excitation of a metallic ruthenium target with 3.0 MeV protons at Variable Energy Cyclotron, Chandigarh. The gamma-ray spectra were measured at 55� to the beam line using a 50 cm 3 Ge(Li) detector (resolution: 2.5 keV at 1332 keV). The present B(E2) values for different states in 99Ru and 101Ru are compared with the values available in the literature.
Arora, B. K.; Mehta, D.; Rani, Rakesh; Cheema, T. S.; Trehan, P. N.
Excitation of interstellar hydrogen chloride
NASA Technical Reports Server (NTRS)
We have computed new rate coefficients for the collisional excitation of HCl by He, in the close-coupled formalism and using an interaction potential determined recently by Willey, Choong, & DeLucia. Results have been obtained for temperatures between 10 K and 300 K. With the use of the infinite order sudden approximation, we have derived approximate expressions of general applicability which may be used to estimate how the rate constant for a transition (J to J prime) is apportioned among the various hyperfine states F prime of the final state J prime. Using these new rate coefficients, we have obtained predictions for the HCl rotational line strengths expected from a dense clump of interstellar gas, as a function of the HCl fractional abundance. Over a wide range of HCl abundances, we have found that the line luminosities are proportional to abundance(exp 2/3), a general result which can be explained using a simple analytical approximation. Our model for the excitation of HCl within a dense molecular cloud core indicates that the J = 1 goes to 0 line strengths measured by Blake, Keene, & Phillips toward the Orion Molecular Cloud (OMC-1) imply a fractional abundance n(HCl)/n(H2) approximately 2 x 10(exp -9), a value which amounts to only approximately 0.3% of the cosmic abundance of chlorine nuclei. Given a fractional abundance of 2 x 10(exp -9), the contribution of HCl emission to the total radiative cooling of a dense clump is small. For Orion, we predict a flux approximately 10(exp -19) W/sq cm for the HCl J = 3 goes to 2 line near 159.8 micrometers, suggesting that the strength of this line could be measured using the Infrared Space Observatory.
Neufild, David A.; Green, Sheldon
Excitement in shame: the price we pay.
This paper explores the role of excitement in shame, extending the theoretical underpinnings of my work (Aledort, 2002, 2003, 2008, 2009) on narcissism and the omnipotent child syndrome. Shame, excitement, and early narcissistic self-states are complexly intermingled, each influencing the other. Empathy alone is insufficient; the passion connected to shame can be easily hidden. Detailed case studies describe a model for working with the excitement in shame, how it functions, and how it gets resolved. PMID:24320576
Aledort, Stewart L
Hybrid Excitation of the Axial Inductor Machine
NASA Astrophysics Data System (ADS)
The paper considers the possibility to use permanent magnets in the rotor slots of axial inductor machine with the aim to create a hybrid excitation of such a machine - from the magnets and from the excitation winding which is placed between the stator cores. The hybrid excitation allows the weight and size parameters of the machine to be improved. Under consideration is a 32 kW under-carriage generator 2?B.13.Y1.
Orlova, S.; Pugachov, V.; Levin, N.
NSDL National Science Digital Library
Learners apply their knowledge from a previous study to identify different liquids--water, corn syrup, and vegetable oil. They also investigate combinations of liquids, two at a time, to see how they interact. This is meant as a follow-up lesson to the related activity, Exploring Liquids. As an extension, learners can continue their study of these liquids in the lesson, Traveling Through Different Liquids.
Janulaw, Sharon
Theoretical model of liquid metals
A theory for calculating the bulk properties of metals and other materials is described. The approach is based upon the fluid perturbation theory of Kerley and the electronic structure model of Liberman. Application of the theory involves three steps. First, the zero Kelvin isotherm of the solid is constructed from electronic structure calculations, experimental data, or both. This curve contains information about the effective interactions between atoms in the ground electronic state. Next, the cold curve is combined with perturbation theory to compute contributions from thermal motion of the atoms to the liquid properties. Finally, contributions from thermal electron excitation are computed using the electronic structure model. This paper shows that theory agrees well with experimental data for xenon and iron.
Kerley, G.I.
Periodic acceptor excitation spectroscopy of single molecules
Alternating-laser excitation (ALEX) spectroscopy has recently been added to the single-molecule spectroscopy toolkit. ALEX monitors interaction and stoichiometry of biomolecules, reports on biomolecular structure by measuring accurate F�rster resonance energy transfer (FRET) efficiencies, and allows sorting of subpopulations on the basis of stoichiometry and FRET. Here, we demonstrate that a simple combination of one continuous-wave donor-excitation laser and one directly modulated acceptor-excitation laser (Periodic Acceptor eXcitation) is sufficient to recapitulate the capabilities of ALEX while minimizing the cost and complexity associated with use of modulation techniques.
Doose, Soren; Heilemann, Mike; Michalet, Xavier; Weiss, Shimon
Rydberg excitation of Bose-Einstein condensates.
Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here, we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore, the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations. PMID:18232977
Heidemann, Rolf; Raitzsch, Ulrich; Bendkowsky, Vera; Butscher, Bj�rn; L�w, Robert; Pfau, Tilman
New excitation method of surface polaritons
NASA Astrophysics Data System (ADS)
A new excitation method is proposed for surface polaritons of an evanescent mode which cannot be excited by the attenuated total reflection method. A thin-film waveguide has been designed and produced to excite surface polaritons of evanescent modes at a Ag-SiO2 interface. If the wave number of the optical guided waves propagating in the dielectric thin-film waveguide (SiO2/Ta2O5/SiO2) is equal to the wave number of the surface polaritons, then a coupling between the two modes occurs. The excitation of the surface polaritons can be confirmed by an attenuation of the optical guided waves.
Nakagawa, Yasuhiko; Kaneko, Michihiro; Terunuma, Noboru
Phase Controlled Laser Interference for Tunable Phase Gratings in Dye-Doped Nematic Liquid Crystals
NASA Astrophysics Data System (ADS)
A phase controlled multi-beam interference is applied to excite the doped liquid crystals. Control of the phase difference between the exciting beams allows the external control of the interference pattern inside the liquid crystal. The dynamic variation of the grating is made possible with a time-dependent phase change to derive the nonlinear refractive index as well as the responding speed of the material. The induced grating structure is numerically modelled with reorientational phase gratings in the liquid crystal, and the diffraction dynamics is found to be in good agreement between theoretical and experimental results.
Li, Ming; Zhang, Pei-Qing; Guo, Jing; Xie, Xiang-Sheng; Liu, Yi-Kun; Liang-Bing; Zhou, Jian-Ying; Xiang, Ying
High-performance liquid chromatographic determination of granisetron in human plasma
This paper describes a high-performance liquid chromatographic method (HPLC) with fluorometric detection for the analysis of granisetron in plasma. The detection is performed at 305 nm for excitation and 365 n, for emission. The method involves sample clean-up by liquid-liquid extraction. N-(1-Naphthyl) ethylenediamine dihydrochloride is used as internal standard. Toluene and phosphate buffer were added to 0.5 ml of plasma
Fr�d�ric Pinguet; Fran�oise Bressolle; Pascal Martel; David Salabert; C�cile Astre
Tuning the Pitch of a Wine Glass by Playing with the Liquid inside
ERIC Educational Resources Information Center
It is well known that the pitch of the sound produced by an excited glass shell can be tuned by adding some liquid in it. In this paper, it will be proved that the distribution of the liquid inside the shell plays a crucial role in this frequency shift. Thus it provides another way to tune the pitch of the sound by modifying the liquid�
Courtois, Matthieu; Guirao, Boris; Fort, Emmanuel
Polarization Raman Spectral Microscopy of Polymer Fibers Formed in Ferroelectric Liquid Crystal
This letter focuses on Raman spectral microscopy of polymer fiber networks, which are formed by the photopolymerization of liquid crystalline acrylate monomers in low-molecular-weight ferroelectric liquid crystal, using polarized infrared light to excite the polymer molecules. It was found that the tolane side-chain molecules of the polymer are significantly orientated with the liquid crystal alignment along the rubbing direction of
Hideo Fujikake; Takeshi Murashige; Hiroto Sato; Masahiro Kawakita; Hiroshi Kikuchi
Liquid-liquid phase transition in water
NASA Astrophysics Data System (ADS)
Water shows anomalies different from most of other materials. Different sceniaros have been proposed to explain water anomalies, among which the liquid-liquid phase transition (LLPT) is the most discussed one. It attributes water anomalies to the existence of a hypothesized liquid-liquid critical point (LLCP) buried deep in the supercooled region. We briefly review the recent experimental and theoretical progresses on the study of the LLPT in water. These studies include the discussion on the existence of the first order LLPT in supercooled water and the detection of liquid-liquid critical point. Simulational results of different water models for LLPT and the experimental evidence in confined water are also discussed.
Sun, ZhaoRu; Sun, Gang; Chen, YiXuan; Xu, LiMei
Rapid prototyping of electrochromatography chips for improved two-photon excited fluorescence detection.
In the present study, we introduce two-photon excitation at 532 nm for label-free fluorescence detection in chip electrochromatography. Two-photon excitation at 532 nm offers a promising alternative to one-photon excitation at 266 nm, as it enables the use of economic chip materials instead of fused silica. In order to demonstrate these benefits, one-photon and two-photon induced fluorescence detection are compared in different chip layouts and materials with respect to the achievable sensitivity in the detection of polycyclic aromatic hydrocarbons (PAHs). Customized chromatography chips with cover or bottom slides of different material and thickness are produced by means of a rapid prototyping method based on liquid-phase lithography. The design of thin bottom chips (180 ?m) enables the use of high-performance immersion objectives with low working distances, which allows one to exploit the full potential of two-photon excitation for a sensitive detection. The developed method is applied for label-free analysis of PAHs separated on a polymer monolith inside polymer glass sandwich chips made from fused silica or soda-lime glass. The obtained limits of detection range from 40 nM to 1.95 ?M, with similar sensitivities in fused silica thin bottom chips for one-photon and two-photon excitation. In deep-UV non- or less-transparent devices two-photon excitation is mandatory for label-free detection of aromatics with high sensitivity. PMID:24666258
Hackl, Claudia; Beyreiss, Reinhild; Geissler, David; Jezierski, Stefan; Belder, Detlev
Prediction of Sloshing and Seismic Response of a Floating Roof in a Cylindrical Liquid Storage Tank by the Response Spectrum Method
A response spectrum method is proposed to predict the sloshing response of a floating roof in a cylindrical liquid storage tank under seismic excitation. The liquid is assumed to be inviscid, incompressible, and irrotational, while the floating roof is considered as an orthotropic elastic plate of variable thickness. The dynamic interaction between the liquid and the floating roof is taken
Tetsuya Matsui
Supersolid structure and excitation spectrum of soft-core bosons in three dimensions
NASA Astrophysics Data System (ADS)
By means of a mean-field method, we have studied the zero-temperature structure and excitation spectrum of a three-dimensional soft-core bosonic system for a value of the interaction strength that favors a crystal structure made of atomic nanoclusters arranged with fcc ordering. In addition to the longitudinal and transverse phonon branches expected for a normal crystal, the excitation spectrum shows a soft mode related to the breaking of gauge symmetry, which signals a partial superfluid character of the solid. Additional evidence of supersolidity is provided by the calculation of the superfluid fraction, which shows a first-order drop, from 1 to 0.4, at the liquid-supersolid transition and a monotonic decrease as the interaction strength parameter is increased. The conditions for the coexistence of the supersolid with the homogeneous superfluid are discussed, and the surface tension of a representative solid-liquid interface is calculated.
Ancilotto, Francesco; Rossi, Maurizio; Toigo, Flavio
Vibrationally Excited Molecular Hydrogen near Herschel 36
NASA Astrophysics Data System (ADS)
We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme rovibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, with this component presumably lying near the star system and undergoing fluorescent excitation. The overall H2 excitation is similar to, but apparently larger than, that seen toward HD 37903 which previously showed the largest vibrationally excited H2 column densities seen in UV absorption spectra. While the velocities of the highly excited H2 lines are consistent within each observation, it appears that they underwent a ~60 km s-1 redshift during the 3.6 yr between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually excited CH and CH+ lines and several unusually broad diffuse interstellar bands toward Herschel 36. Along with the H2 excitation, all of these findings appear to be related to the extreme environment within ~0.1 pc of the massive young stellar system.
Rachford, Brian L.; Snow, Theodore P.; Ross, Teresa L.
Laser-excited synchronous luminescence spectroscopy
The use of lasers as excitation sources for molecular luminescence often results in improvements in sensitivity and limits of detection (LODs). Synchronous luminescence (SL) spectroscopy, in which both excitation and emission wavelengths are scanned simultaneously, provides a convenient means to improve selectivity (often dramatically) in the analysis of multicomponent mixtures using room-temperature luminescence. The authors report here on the first
Christopher L. Stevenson; Tuan Vo-Dinh
Invasion Waves in Populations with Excitable Dynamics
Whilst the most obvious mechanism for a biological invasion is the occupation of a new territory as a result of direct ingress by individuals of the invading population, a more subtle �invasion� may occur without significant motion of invading individuals if the population dynamics in a predator prey scenario has an �excitable� character. Here, �excitable� means that a local equilibrium
J. Brindley; V. H. Biktashev; M. A. Tsyganov
Excited hadrons on the lattice: Mesons
We present results for masses of excited mesons from quenched calculations using chirally improved quarks at pion masses down to 350 MeV. The key features of our analysis are the use of a matrix of correlators from various source and sink operators and a basis which includes quark sources with different spatial widths, thereby improving overlap with states exhibiting radial excitations.
Burch, Tommy; Hagen, Christian; Schaefer, Andreas [Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); Gattringer, Christof; Glozman, Leonid Ya.; Lang, C.B. [Institut fuer Physik, FB Theoretische Physik, Universitaet Graz, A-8010 Graz (Austria)
Plasma wakefield excitation by charge particle beams
Electron plasma waves excited by a charge bunch are studied analytically and via computer simulations in full generality. Analytic results of plasma wakefield excitation are compared with particle-in-cell computer simulations both qualitatively and quantitatively. Doppler shifts and the nonlinear properties of plasma waves are included. One of the major goals is to study plasma applications to high energy physics. Accelerator
Jao-Jang Su; Jaojang
Configurational statistics of excited granular materials
In this dissertation, we investigate theories of configurational statistics for excited granular materials, and test the predictions with extensive molecular dynamics (MD) simulations. First we examine a system of weakly excited granular materials in a vibrating bed. We use a thermodynamic theory of hard spheres, which explores consequences of the excluded volume interaction under gravity. The global temperature T, is
Paul Victor Quinn
The excited random walk in one dimension
We study the excited random walk, in which a walk that is at a site that contains cookies eats one cookie and then hops to the right with probability p and to the left with probability q = 1 - p. If the walk hops onto an empty site, there is no bias. For the 1-excited walk on the half-line
Tibor Antal; S. Redner
Collisional energy transfer from excited nitrogen dioxide.
National Technical Information Service (NTIS)
The radiative lifetimes of gaseous nitrogen dioxide excited by pulsed, tunable dye laser radiation are determined for excitation wavelengths ranging from 400 to 750 nm. When the data are expressed in the form of zero-pressure radiative rate constants (k(s...
K. O. Patten
Excitation Mechanisms in Pulsed CO2 Lasers
Experimental studies were carried out on laser systems to investigate the excitation mechanisms of the upper laser level (0001) of carbon dioxide in an electrical discharge, and the parts played by helium and nitrogen in mixed systems. Used as constituent gases were carbon dioxide, carbon dioxide-nitrogen, and carbon dioxide-helium. Pulsed electrical excitation was used with an arrangement for varying the
William B. McKnight; Redstone Arsenal; C. K. N. Patel
Making Excited Oxygen Molecules And Atoms
NASA Technical Reports Server (NTRS)
Oxidation of semiconductors and high-temperature superconductors achieved at lower temperatures by use of oxygen molecules or atoms raised into specific excited states. Use of excited oxygen (or other species) of interest in research on kinetics and mechanisms of chemical reactions. Used in ultra-high-vacuum chamber also equipped for such surface-analytical techniques as x-ray photoelectron spectroscopy.
Vasquez, Richard P.
Nuclear excitations and reaction mechanisms
The main theme of this report is the study and interpretation of the sequence of events that occur during the collisions of nuclear particles. Some of the processes discussed in parts A and B involve short range interactions; others involve interactions of long range. In most of part A one of the particles in the initial or in the final state (or in both) is a photon, which serves as a probe of the second particle, which may be a nucleus, a proton, a pion or any other hadron. The complexity of the processes taking place during the collisions makes it necessary to simplify some aspects of the physical problem. This leads to the introduction of modals which are used to describe a limited number of features in as much detail as possible. The main interest is the understanding of the hadronic excitations which result from the absorption of a photon and the determination of the fundamental structure constants of the target particle. In part B, all the particles are hadrons. The purpose here is to develop and apply optimal quantal methods appropriate for describing the interacting systems. Of particular interest are three-particle collision systems in which the final state consists of three free particles. Part B also considers the process of nuclear fusion as catalyzed by bound muons.
Fallieros, S.; Levin, F.S.
Multi-photon excitation microscopy
Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments.
Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare
Discharge excitation of dye vapors
NASA Astrophysics Data System (ADS)
Experiments have been conducted to assess the feasibility of obtaining a discharge-pumped dye vapor laser. A 15 (or 50) cm active length, UV-preionized device has been developed which exhibits a specific power loading of the medium of approx. 5 MW/cu cm and will operate continuously at temperatures exceeding 400 C. Recently, hydrogen thyratron switching of the device and corona preionization have been installed to minimize jitter and dye fragmentation. Optimization of the rare gas/N2 diluent mixture has been completed and fragmentation studies for several dye molecules have been conducted. POPOP and alpha-NPO are excellent in the latter regard but Coumarin 6 rapidly decomposes in the discharge environment. The fluorescence efficiency of alpha-NPO is only 40 percent of that for POPOP under comparable conditions. BBO and PBBO are similar in structure and molecular weight to POPOP and appear to be excellent candidates for discharge excitation. Fluorescence and small signal gain measurements are in progress.
Eden, J. G.
A liquid level detector for low pressure boilers. A boiler tank, from which apor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.
Grasso, Albert P. (Vernon, CT) [Vernon, CT
A liquid level detector for low pressure boilers. A boiler tank, from which vapor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.
Grasso, A.P.
Semiconductor nanorod liquid crystals
Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.
Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul
Charge transfer reactions in nematic liquid crystals
Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.
Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.]|[Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry
Renyi entropy of gapless spin liquids
NASA Astrophysics Data System (ADS)
Spin liquids are exotic quantum states that do not break any symmetry. Though much is known about gapped spin-liquids, critical spin-liquids with strongly interacting gapless excitations in two and three spatial dimensions are less understood. Candidate ground state wave-functions for such states however can be constructed using the Gutzwiller projection method. We use bipartite entanglement entropy, in particular the Renyi entropy S2 to investigate the quantum structure of these wave-functions. Using the Variational Monte-Carlo technique, we calculate the Renyi entropy of a critical spin liquid - the projected Fermi sea state on the triangular lattice. We find a violation of the boundary law, with S2 enhanced by a logarithmic factor, an unusual result for a bosonic wave-function reflecting the presence of emergent spinons that form a Fermi surface. The Renyi entropy for algebraic spin liquids is found to obey the area law, consistent with the presence of emergent Dirac fermions in the system. Projection is found to completely alter the entanglement properties of nested Fermi surface states. These results show that the Renyi entropy calculations could serve as a diagnostic for gapless fractionalized phases.
Grover, Tarun; Zhang, Yi; Vishwanath, Ashvin
Elementary excitations and phase transitions in crystals
The unique method of measuring elementary excitations in solids over a wide range of energy and momentum transfers is inelastic scattering of neutrons. Elementary excitations are defined as a correlated motion of atoms or spins in a solid which include phonons, magnons, rotons, or crystal field excitations. These excitations play a fundamental role in a wide variety of structural and magnetic phase transitions and provide the information in understanding the underlying microscopic mechanism of the transformation. Below, I shall review some of the relevant aspects of neutron scattering formalism related to inelastic neutron scattering and demonstrate how it has been applied to the study of phase transitions in crystals. I shall give two examples of structural phase transitions where the phonons are the elementary excitations and studies in a conventional superconductor where the phonon linewidths are a measure of the electron-phonon coupling responsible for the pairing.
Shapiro, S.M.
Dissociative ionization of water induced by single-photon vibrational excitation
Vibrational photochemistry of pure liquid water to produce H\\/sup +\\/ and OH⁻ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. The quantum yield at 283 +- 1 K varies from 2 x 10⁻⁹ to 4 x 10⁻⁵ for wavenumbers betwen 7605 and 18,140 cm⁻¹. The quantum yield rises through the low-frequency side of an absorption
Wesley C. Natzle; C. Bradley Moore; D. M. Goodall; W. Frisch; J. F. Holzwarth
Investigation of self-excited combustion instabilities in two different combustion systems
The objective of this paper is to characterize dynamic pressure traces measured at self-excited combustion instabilities occurring\\u000a in two combustion systems of different hardware. One system is a model lean premixed gas turbine combustor and the other a\\u000a fullscale bipropellant liquid rocket thrust chamber. It is commonly observed in both systems that low frequency waves at around\\u000a 300Hz are first
Seonghyeon Seo
Variational theory of valence fluctuations: Ground states and quasiparticle excitations of the Anderson lattice model
A variational study of ground states of the orbitally nondegenerate Anderson lattice model, using a wave function with one variational parameter per Bloch state k, has been extended to deal with essentially metallic systems having a nonintegral number of electrons per site. Quasiparticle excitations are obtained by direct appeal to Landau's original definition for interacting Fermi liquids, scrE/sub qp/(k,sigma) = deltaE/sub total//deltan qp(k,sigma).
Brandow, B.H.
Increasing average power in medical ultrasonic endoscope imaging system by coded excitation
NASA Astrophysics Data System (ADS)
Medical ultrasonic endoscope is the combination of electronic endoscope and ultrasonic sensor technology. Ultrasonic endoscope sends the ultrasonic probe into coelom through biopsy channel of electronic endoscope and rotates it by a micro pre-motor, which requires that the length of ultrasonic probe is no more than 14mm and the diameter is no more than 2.2mm. As a result, the ultrasonic excitation power is very low and it is difficult to obtain a sharp image. In order to increase the energy and SNR of ultrasonic signal, we introduce coded excitation into the ultrasonic imaging system, which is widely used in radar system. Coded excitation uses a long coded pulse to drive ultrasonic transducer, which can increase the average transmitting power accordingly. In this paper, in order to avoid the overlapping between adjacent echo, we used a four-figure Barker code to drive the ultrasonic transducer, which is modulated at the operating frequency of transducer to improve the emission efficiency. The implementation of coded excitation is closely associated with the transient operating characteristic of ultrasonic transducer. In this paper, the transient operating characteristic of ultrasonic transducer excited by a shock pulse ?(t) is firstly analyzed, and then the exciting pulse generated by special ultrasonic transmitting circuit composing of MD1211 and TC6320. In the final part of the paper, we designed an experiment to validate the coded excitation with transducer operating at 5MHz and a glass filled with ultrasonic coupling liquid as the object. Driven by a FPGA, the ultrasonic transmitting circuit output a four-figure Barker excitation pulse modulated at 5MHz, +/-20 voltage and is consistent with the transient operating characteristic of ultrasonic transducer after matched by matching circuit. The reflected echo from glass possesses coded character, which is identical with the simulating result by Matlab. Furthermore, the signal's amplitude is higher.
Chen, Xiaodong; Zhou, Hao; Wen, Shijie; Yu, Daoyin
Plate Performance in Liquid-Liquid Extraction.
National Technical Information Service (NTIS)
The relative effectiveness of perforated, nozzle, and burred plates from a capacity and extraction standpoint were studied in a pulsed liquid-liquid extraction system. The experiments were conducted in a 3.8 x 10 exp -2 m diameter column using a mixture o...
R. P. Wadkins
The interaction of elastic waves with a solid-liquid interface, with applications to the core-mantle boundary
The paper discusses basic ideas and principles underlying methods, which have proved useful in the interpretation of diffraction and scattering phenomena by a smooth or slightly rough solid-liquid interface. Generally, the wave interaction may be formulated as an excitation problem; it involves (1) finding an equivalent dislocation or source distribution on the interface, and (2) evaluating the excited wave field.
D. J. Doornbos; J. C. Mondt
Fast Laser Excitation and Ultrahigh Strain-Rate Deformation
Phase evolution induced by single or repeated excitation with energetic femtosecond laser pulses is examined. Of primary interest is the solidification behavior of pure metals at deep undercoolings and self-organization in simple eutectic alloys. Time resolved measurements using third harmonic generation (THG) of light and ultrafast electron diffraction (UED) are employed to elucidate several issues related to fast laser excitation, including heat transport by ballistic and diffusional electrons through multilayer films, the dependence of crystallization velocities on materials properties, mechanisms controlling the transport of heat away from the crystal-liquid interface, and the possibility for quenching pure metals, such as Cu, Ni, and Fe, into the amorphous state. Special samples designed to maximize the quenching speed are developed. The properties of such pure metallic glasses, such as glass and crystallization temperatures, will be measured, if such samples are successfully produced. The measurements are complemented by molecular dynamics computer simulations of the solidification process. The second interest of this research is mesoscopic, self-organization of materials under repeated laser melting, with diffusional relaxation between pulses. We select binary alloys that are immiscible in the solid state but miscible in the liquid state, such as Ag-Cu. Femtosecond laser irradiation is employed to induce melting and to vary the melting time over a wide range, from a few ps to hundreds of ps. This enables us to perform critical experimental tests of key theoretical predictions self-organization in alloys under external forcing, in particular the existence of a threshold value of the forced mixing length for patterning to take place.
Robert Averback
Portable liquid dispensing kit
US Patent & Trademark Office Database
A portable kit for transporting and dispensing liquid concentrates for beverage mixing includes receptacles for liquid concentrate containers has locking mechanisms for sealing the containers while not in use, as well as, a removable drip tray with a removable grate.
Liquid medication administration
... easily. Oral syringes have some advantages for giving liquid medications. They are accurate. They are easy to ... cups are also a handy way to give liquid medications. However, dosing errors have occurred with them. ...
NASA Technical Reports Server (NTRS)
An atomizer for a liquid having an air supply is described. Liquid supply tubes extend longitudinally along the air supply tube. The air supply tube has at least one air orifice extending from an inner surface of the tube through the tube. The liquid supply tubes are positioned on either side of the air orifices and the liquid tubes are sealed to the air supply tube. The liquid supply tubes with facing liquid orifices are positioned adjacent to each of the air orifices. The liquid supply tubes are laterally spaced apart at the liquid orifices at a distance less than the diameter of the air orifices to enable a beneficial venturi effect when the atomizer is in operation.
Seegmiller, Henry L. B. (inventor)
National Technical Information Service (NTIS)
Given here is a definition of Liquid Air Cycle Engines (LACE) and existing relevant technologies. Heat exchanger design and fabrication techniques, the handling of liquid hydrogen to achieve the greatest heat sink capabilities, and air decontamination to ...
J. Rosevear
National Technical Information Service (NTIS)
A study of the electrooptic properties of liquid crystals and their potential in several Navy device applications is described. Experimental work in the evaporation and sputtering of photoconductive films for the photoactivation of a liquid crystal device...
M. A. Monahan H. H. Caspers L. B. Stotts M. N. McLandrich
National Technical Information Service (NTIS)
A flexible liquid crystal display is provided wherein an addressable liquid crystal layer is disposed on a single flexible substrate so that the display itself will exhibit flexibility. The substrate is preferably a flexible non-transparent material and m...
A. Green A. A. Khan I. Shiyanovskaya J. W. Doane
Terahertz Spectroscopy of Excited Water
NASA Astrophysics Data System (ADS)
The observation and characterization of water spectra have been intensely pursued in the astrophysical community. Its rotational transitions in the ground, (010) (v_2 = 1), (020), (100), and (001) states are primary targets of the ongoing Herschel mission. In this study, laboratory terahertz spectroscopy of water was carried out at JPL and Cologne, with the goals to measure all transitions HIFI might see and critically review and fit the lowest 5 vibrational states. DC discharge, radio frequency discharge and heating tapes were used to generate highly excited water. A total of 145 pure rotational transitions in the (000), (010), (020), (100), and (001) states of water were observed in the 293-1969 GHz region. Of these, 86 have been detected for the first time with MW accuracy. So far, the 1(1,0)-1(0,1) transition was observed for all five states; the 2(1,2)-1(0,1) transition was observed for (000), (100), and (001) but is missing for (010) (1753914 GHz) and (020) (1872972 GHz); the 1(1,1)-0(0,0) transition was observed for all states but (020) (1332967 GHz). The analysis is still in progress, and we will present the most recent fitting results to date. There are difficulties in fitting water spectra, such as the strong centrifugal distortion, which gives a non-convergent Watson Hamiltonian. In addition, the first triad states (100, 020, and 001) are strongly coupled. The latest attempt at a global fit of these 5 states using Euler series achieved a reduced RMS of 8.4 (Pickett et al. 2005, J. Mol. Spectrosc. 233, 174).
Yu, Shanshan; Pearson, John C.; Drouin, Brian J.; Walters, Adam; M�ller, Holger S. P.; Br�nken, Sandra
Continuous wave-based multiphoton excitation fluorescence for capillary electrophoresis.
It was reported that a novel detection method, continuous wave (CW)-based multiphoton excitation (MPE) fluorescence detection with diode laser (DL), has been firstly proposed for capillary electrophoresis (CE). Special design of end-column detection configuration proved to be superior to on-column type, considering the detection sensitivity. Three different kinds of fluorescent tags that were widely used as molecular label in bio-analysis, such as small-molecule dye, fluorescent protein and nano particle or also referred to as quantum dot (QD), have been evaluated as samples for the constructed detection scheme. Quantitative analyses were also performed using rhodamine species as tests, which revealed dynamic linear range over two orders of magnitude, with detection limit down to zeptomole-level. Simultaneous detection of fluorescent dyestuffs with divergent excitation and emission wavelengths in a broad range showed advantage of this scheme over conventional laser-induced fluorescence (LIF) detection. Further investigations on CW-MPE fluorescence detection with diode laser for capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations of fluorescein isothiocyanate (FITC) labeled amino acids indicated good prospect of this detection approach in various micro or nano-column liquid phase separation technologies. PMID:16325835
Chen, Sheng; Liu, Bi-Feng; Fu, Ling; Xiong, Tao; Liu, Tiancai; Zhang, Zhihong; Huang, Zhen-Li; Lu, Qiang; Zhao, Yuan-Di; Luo, Qingming
Decay widths of highly excited Ra compound nuclei
NASA Astrophysics Data System (ADS)
Excitation functions were obtained for the xn, p xn and ?xn decay channels of 216,218,220Ra compound nuclei produced in the reactions 22Ne+ 194,196,198Pt in the excitation energy range of 40-160 MeV. Due to the employment of three platinum isotope targets, the cross section ratios were measured with a high degree of accuracy for evaporation reaction channels resulting in the formation of fixed cold products after the termination of evaporation cascades of a different numbers of stages. Experimental values for the reduced neutron widths of highly excited compound nuclei were obtained from the measured cross section ratios. Evaporation reaction cross sections were well described in the framework of the statistical model taking into account shell effects according to Ignatyuk. Our present, and also earlier, investigations showed that calculations making use of one single set of the model parameters (the scaling factor to the liquid-drop fission barrier of Cohen, Plasil and Swiatecki, C = 0.6-0.7 and the ratio of the level density parameters, {overlineaf}/{overlineav} = 1.0 ) reproduces correctly the cross sections of the evaporation reactions in a wide range of compound nuclei extending from Bi to U. Moreover, the measured cross section ratios are exceptionally sensitive to the value of the parameter {overlineaf}/{overlineav}, i.e. are very suitable for a high accuracy estimation of this value. By fitting two sets of the experimental data � the absolute cross section values and cross section ratios � we were able to independently estimate the values of two principal parameters of the model, C and {overlineaf}/{overlineay}. Our calculations showed that a large part of the pre-fission neutrons is evaporated by hot pre-actinide compound nuclei before they reach the saddle point (50 to 100% of the total number of pre-fission neutrons are pre-saddle).
Andreyev, A. N.; Bogdanov, D. D.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Muzichka, Yu. A.; Oganessian, Yu. Ts.; Popeko, A. G.; Pustylnik, B. I.; Sagaidak, R. N.; Ter-Akopian, G. M.; Yeremin, A. V.
Clear liquid diet ... A clear liquid diet is made up of only clear fluids and foods that turn to clear fluids when they are ... you need for energy. Eating only a clear liquid diet gives you enough nutrition for 3 to ...
Thermochromic liquid crystals have been exploited in novelties and in high-technology applications alike since the earliest years of liquid crystal technology. They have also played a central role in the elucidation of the structures of liquid crystal phases and their inter-relationship, the optics of mesophases, the nature of phase transitions and their static and dynamic continuum theory. Despite this long
Ian Sage
Volatile liquid storage system
This patent describes a method of collecting and abating emission from a volatile liquid in an above ground storage tank. It comprises the liquid storage tank having a bottom, a vertical cylindrical circular wall having a lower edge portion joined to the bottom, and an external fixed roof, the tank having an internal floating roof floating on a volatile liquid
R. J. Laverman; P. J. Winters; J. K. Rinehart
Supergluing MOF liquid marbles.
Growth of NH(2)-MIL-53(Al) on alumina microparticles followed by post-synthetic modification with perfluorooctyl or caproic groups produces highly hydrophobic microparticles which are utilized for the formation of liquid marbles. Interfacial polymerization of ethyl-2-cyanoacrylate on the surface of the liquid marbles produces stable liquid capsules. PMID:23202539
Chin, Jia Min; Reithofer, Michael R; Tan, Tristan Tsai Yuan; Menon, Ajay Govinda; Chen, Eric Yu; Chow, Chin Ann; Hor, Andy Tzi Sum; Xu, Jianwei
National Technical Information Service (NTIS)
An atomizer for a liquid having an air supply is described. Liquid supply tubes extend longitudinally along the air supply tube. The air supply tube has at least one air orifice extending from an inner surface of the tube through the tube. The liquid supp...
H. L. B. Seegmiller
Herein is a circuit which is capable of detecting the presence of liquids, especially cryogenic liquids, and whose sensor will not overheat in a vacuum. The circuit parameters, however, can be adjusted to work with any liquid over a wide range of temperatures.
Regan, Thomas O. (North Aurora, IL)
Electrically Deformable Liquid Marbles
Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. The semi-quantitative theory describing deformation of liquid marbles in a uniform
Edward Bormashenko; Roman Pogreb; Tamir Stein; Gene Whyman; Marcelo Schiffer; Doron Aurbach
Liquid Nitrogen Level Controller.
National Technical Information Service (NTIS)
The liquid nitrogen level in a flask is controlled by the degree of immersion of two sensing coils of copper wire in the liquid nitrogen, activating a solid state switching circuit which controls a liquid nitrogen inlet flow valve. Manual override and sen...
D. Sears
PREFACE: 6th Liquid Matter Conference
NASA Astrophysics Data System (ADS)
This special issue of Journal of Physics: Condensed Matter contains the Proceedings of the 6th Liquid Matter Conference held in Utrecht, The Netherlands, 2-6 July 2005. The three-yearly Liquid Matter Conference is organized by the Liquids Section of the Condensed Matter Division of the European Physical Society. This series of meetings began in Lyon in 1990. The most recent meeting was held in 2003 in Konstanz. The aim of the Liquid Matter Conferences is to bring together scientists working on the liquid state of matter. This rapidly growing field includes the physics, chemistry, biology and chemical engineering of liquid matter as well as various applied research areas. In fact, the Utrecht meeting had, for the first time, a special session devoted to Fundamental Challenges in Applied Liquid Physics and Microfluidics. The Utrecht meeting had 760 registered participants from four continents. An important event at this meeting was the award of the First Liquid Matter Prize of the European Physical Society to Professor Jean-Pierre Hansen FRS, of Cambridge University. In addition to a plenary speech by the recipient of the Liquid Matter Prize, the scientific programme consisted of 10 plenary lectures, 117 symposia talks, 25 of which were keynote lectures and some 650 poster contributions. The meeting also hosted a one-day symposium of the Division of Liquids and Interfaces of the Chemical Sciences division of NWO. This special issue of Journal of Physics: Condensed Matter contains 61 of the oral communications. Liquid state physics is at the interface of many fields of research. As a consequence, many of the attendants come from adjacent fields and find in the Liquid Matter Conference a forum to meet experts from other areas of research. This aspect of the Liquid Matter Conference makes it an exciting meeting as it not only offers the participants an up-to-date picture of the status of research into the liquid state of matter, but it also allows them to establish new (and often unexpected) trans-disciplinary contacts for joint scientific endeavours. This applies in particular to the area of soft condensed matter such as colloidal suspensions, polymeric systems and biological materials. The conference was held at the Uithof, the campus of the University of Utrecht. The organizers gratefully acknowledge the generosity of the University and City of Utrecht, which enabled us to stage both the scientific part of the conference and several festive and cultural events in some of the most attractive venues of the Netherlands. We were also delighted by the substantial contributions offered by the sponsors of the 6th Liquid Matter Conference. With this support it became possible to support a large number of scientists who would otherwise not have been able to attend. Finally, we owe a great debt of gratitude to the secretarial staff of the conference and the many students, postdocs and other colleagues who helped tirelessly (and very efficiently) to make the conference run smoothly. The Board of the Liquids Section of the European Physical Society decided that the 7th Liquid Matter Conference will be held in Lund (Sweden). The tentative dates are Friday 27 June 2008 to Tuesday 1 July 2008.
Dijkstra, Marjolein; van Roij, Ren�; Vroege, Gert Jan; Lekkerkerker, Henk; Frenkel, Daan
Room Temperature Single-Photon Source: Single-Dye Molecule Fluorescence in Liquid Crystal Host
OAK-(B204)We report on new approaches toward an implementation of an efficient, room temperature, deterministically polarized, single-photon source (SPS) on demand-a key hardware element for quantum information and quantum communication. Operation of a room temperature SPS is demonstrated via photon antibunching in the fluorescence from single terrylene-dye molecules embedded in a cholesteric liquid crystal host. Using oxygen-depleted liquid crystal hosts, dye-bleaching was avoided over the course of more than 1 h of continuous 532-nm excitation. Liquid crystal hosts (including liquid crystal oligomers/polymers) permit further increase of the efficiency of the source: (1) by aligning the dye molecules along a direction preferable for the maximum excitation efficiency; (2) by tuning a one-dimensional (1-D) photonic-band-gap microcavity of planar-aligned cholesteric (chiral nematic) liquid crystal layer to the dye fluorescence band.
Lukishova, S.G.; Schmid, A.W.; McNamara, A.J.; Boyd, R.W.; Stroud, C.R.Jr.
First Evidence of Double Spin Isospin Excitation
NASA Astrophysics Data System (ADS)
To study double spin-isospin responses in view of the ??0? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher ?L excitations.
Takahisa, Keiji
Spin excitations in di-nuclear systems
The spin excitations of products from two-body reactions have two sources: transfer of orbital motion into intrinsic spins via tangential friction and thermal excitations of di-nuclear spin modes. The relative importance of these two mechanisms is discussed for deep inelastic scattering, quasi-fission and spontaneous fission processes. The results of simple model calculations are compared to measured {gamma}-multiplicities in {sup 238}U induced quasi-fission reactions and it is concluded that the spin-excitation are only partially equilibrated during the interaction. 11 refs., 5 figs.
Back, B.B.
Optical properties of liquid carbon measured by femtosecond spectroscopy
NASA Astrophysics Data System (ADS)
A comprehensive report of femtosecond time-resolved reflectivity and transmission of graphite and diamond following optical excitation above critical melting fluences Fm of 0.13 and 0.63 J/cm2, respectively, is presented. Normal- and oblique-incidence reflectivity has been measured with 100-fs resolution at wavelengths ranging from 700 to 310 nm. Within 1 ps following excitation above Fm, probe reflectance increases sharply at visible frequencies, remains nearly unchanged at near-ultraviolet frequencies, and depends weakly on excitation fluence. These optical changes are interpreted as an ultrafast melting transition from crystalline graphite or diamond to a common, more reflective liquid state. During the first picosecond following excitation, electron and lattice temperatures substantially equilibrate, and the lattice melts, before heat conducts out of the absorbing volume or the surface hydrodynamically expands. A Drude model of the reflectance spectrum 1 ps after excitation reveals a strongly damped plasma (plasma frequency-relaxation time product ?p?~1), in contrast to liquid silicon (?p?~5). Inferred electron mean free paths approach the average interatomic spacing (2 �), implying electron localization. Optically determined dc resistivities up to 625+/-75 ?? cm agree with measurements at kilobar ambient pressure, but significantly exceed resistivities measured and calculated at low pressure. Thus, the attribution ``metal'' is questionable for fluid carbon under these conditions. The results demonstrate that femtosecond lasers can extend condensed-matter thermophysics measurements to temperature-pressure regimes inaccessible by other methods.
Reitze, D. H.; Ahn, H.; Downer, M. C.
Propagation of a liquid-liquid explosion
Direct contact between two liquids, one cold and the other hot, may be precluded by the presence of a vapor film. Bridging of this film by one or both fluids results in rapid local boiling, which may initiate a propagating liquid-liquid explosion. A mechanism is discussed for the propagation that involves implosion of the film, rapid mixing of the fluids, heat exchange to warm the cold fluid above the temperature for spontaneous nucleation, and the explosive generation of vapor, which in turn continues to sustain the film implosion. Plausibility for the model is demonstrated by means of numerical studies by high-speed computer.
Harlow, F.H.; Ruppel, H.M.
Science Shorts: Comparing Liquids
NSDL National Science Digital Library
Children experience the physical properties of liquids as they watch raindrops run down a window, observe how insects can walk on water, and notice how the "shape" of a liquid matches the container in which it is held. Thinking about similarities and differences among liquids helps to build foundational ideas of matter and molecular structure. In the following lesson, students explore the cohesiveness and surface tension of two liquids. Through observations and interactions, students develop an understanding about how liquids are similar and different.
Adams, Barbara
A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.
Koster, J.E.; Bolton, R.D.
A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans.
Koster, James E. (Los Alamos, NM); Bolton, Richard D. (Los Alamos, NM)
Vibrational energy relaxation of large-amplitude vibrations in liquids
NASA Astrophysics Data System (ADS)
Given the limited intermolecular spaces available in dense liquids, the large amplitudes of highly excited, low frequency vibrational modes pose an interesting dilemma for large molecules in solution. We carry out molecular dynamics calculations of the lowest frequency (``warping'') mode of perylene dissolved in liquid argon, and demonstrate that vibrational excitation of this mode should cause identifiable changes in local solvation shell structure. But while the same kinds of solvent structural rearrangements can cause the non-equilibrium relaxation dynamics of highly excited diatomic rotors in liquids to differ substantially from equilibrium dynamics, our simulations also indicate that the non-equilibrium vibrational energy relaxation of large-amplitude vibrational overtones in liquids should show no such deviations from linear response. This observation seems to be a generic feature of large-moment-arm vibrational degrees of freedom and is therefore probably not specific to our choice of model system: The lowest frequency (largest amplitude) cases probably dissipate energy too quickly and the higher frequency (more slowly relaxing) cases most likely have solvent displacements too small to generate significant nonlinearities in simple nonpolar solvents. Vibrational kinetic energy relaxation, in particular, seems to be especially and surprisingly linear.
Zhang, Baofeng; Stratt, Richard M.
Time-resolved laser-excited Shpol'skii spectrometry with a fiber-optic probe and ICCD camera
Improved methodology for chemical analysis via laser-excited Shpol'skii spectrometry is reported. The complications of traditional methodology for measurements at liquid nitrogen temperature are avoided by freezing the distal end of a bifurcated fiber-optic probe directly into the sample matrix. Emission wavelength-time matrices were rapidly collected by automatically incrementing the gate delay of an intensified charge-coupled device (ICCD) camera relative to the laser excitation pulse. The excitation source is a compact frequency-doubled tunable dye laser whose bandwidth (<0.03 nm) is well matched for Shpol'skii spectroscopy. Data reproducibility for quantitative analysis purposes and analytical figures of merit are demonstrated for several polycyclic aromatic hydrocarbons at 77 K. Although not attempted in this study, time-resolved excitation-emission matrices could easily be collected with this instrumental system. (c) 2000 Society for Applied Spectroscopy.
Bystol, Adam J. [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States)] [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States); Campiglia, Andres D. [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States)] [Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105 (United States); Gillispie, Gregory D. [Dakota Technologies, Inc., 2201A 12th St. N., Fargo, North Dakota 58102-1803 (United States)] [Dakota Technologies, Inc., 2201A 12th St. N., Fargo, North Dakota 58102-1803 (United States)
NSDL National Science Digital Library
The homepage of the Liquid Crystal Institute (LCI) presents gorgeous color images produced from liquid crystal, research overviews, technology invention abstracts, news and conference links, and more. LCI is part of a consortium, selected by the National Science Foundation, based at the Center for Advanced Liquid Crystalline Optical Materials (ALCOM) at Kent State University. The consortium includes Kent State University, Case Western Reserve University, and the University of Akron. ALCOM focuses on interdisciplinary research and development of liquid crystal optoelectronic materials, technology, and consumer products. A few of the liquid crystal studies featured here are fine structure and oily streak defects, magneto-optic response, text display applications, and organic synthesis. One of LCI's projects, the Polymers and Liquid Crystals Textbook, was featured in the December 13, 1996 Scout Report for Science & Engineering The LCI Website is not especially well-organized, but it contains lots of information about liquid crystal technology.
Liquids flow, and in this sense are close to gases. At the same time, interactions in liquids are strong as in solids. The combination of these two properties is believed to be the ultimate obstacle to constructing a general theory of liquids. Here, we adopt a new approach: instead of focusing on the problem of strong interactions, we zero in on the relative contributions of vibrational and diffusional motion. We show that liquid energy and specific heat are given, to a very good approximation, by their vibrational contributions as in solids over almost entire range of relaxation time in which liquids exist as such, and demonstrate that this result is consistent with liquid entropy exceeding solid entropy. Our analysis therefore reveals an interesting duality of liquids not hitherto known: they are close to solids from the thermodynamic perspective and to flowing gases. We discuss several implications of this result.
Trachenko, K.; Brazhkin, V. V.
NASA Astrophysics Data System (ADS)
The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ~10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability.
Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X.; Li, Ju
Liquid Propellant Manipulated Acoustically
NASA Technical Reports Server (NTRS)
Fluids are difficult to manage in the space environment. Without gravity, the liquid and gas do not always remain separated as they do in the 1g environment of Earth. Instead the liquid and gas volumes mix and migrate under the influence of surface tension, thermodynamic forces, and external disturbances. As a result, liquid propellants may not be in a useable location or may even form a chaotic mix of liquid and gas bubbles. In the past, mechanical pumps, baffles, and a variety of specialized passive devices have been used to control the liquid and gas volumes. These methods need to be carefully tuned to a specific configuration to be effective. With increasing emphasis on long-term human activity in space there is a trend toward liquid systems that are more flexible and provide greater control. We are exploring new methods of manipulating liquids by using the nonlinear acoustic effects achieved by using beams of highly directed high-intensity acoustic waves.
Oeftering, Richard C.; Chato, David J.; Mann, Adin, III
NASA Technical Reports Server (NTRS)
Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.
Morris, B. G.
Collisional ionization of electron-excited atoms
NASA Astrophysics Data System (ADS)
Results of experimental studies of the ionization of laser-excited alkali metal ions in collisions with electronegative molecules are reviewed. In particular, attention is given to the physical mechanisms of the formation of ion pairs, characteristics of chemiionization processes involving excited atoms, and experimental studies of the collisional ionization of beams of Li and Na atoms by various electronegative molecules (e.g., O2, SO2, NO3, F2, Cl2, SF6, and CH3Br) during the single- and two-stage resonance excitation of CW and pulsed organic dye lasers. Applications of laser-induced collisional ionization processes to the three-dimensional diagnostics of molecular beams, detection of vibrationally excited molecules, formation of optogalvanic signals in flames, and laser separation of isotopes are discussed.
Beterov, I. M.; Fateev, N. V.
On Response of Structures to Stationary Excitation.
National Technical Information Service (NTIS)
Stationary responses of single- and multi-degree-of-freedom structures subjected to stationary input excitations are studied. Using a modal superposition procedure, closed form solutions for the first three spectral moments of response to white-noise and ...
A. D. Kiureghian
Relations among theories of excitation transfer.
National Technical Information Service (NTIS)
Recent applications of the generalized master equation (GME) theory for the transfer of excitation interacting linearly with phonons results in revision of some previous conclusions about relations between GME and other advanced theories: Haken-Strobl-Rei...
I. Barvik V. Capek
Excited states of positronic lithium and beryllium.
Using a variational method with an explicitly correlated Gaussian basis, we study the e(+)-Li and e(+)-Be complexes in the ground and lowest excited states with higher spin multiplicity. Our calculations provide rigorous theoretical confirmation that a positron can be attached to the excited states: 1s2s2p 4P(o) and 1s�2s2p 3P(o) for e(+)-Li and e(+)-Be, respectively. The result is particularly notable for the e(+)-Be complex, as the excited 3P(o) state lies below the autoionization threshold. We report accurate binding energies, annihilation rates and structural properties of these positron-atom systems. The existence of the ground and metastable excited states with bound positron opens up a new route to the presently lacking experimental verification of stability of a positron binding to any neutral atom. PMID:24266470
Bubin, Sergiy; Prezhdo, Oleg V
Excited States of Positronic Lithium and Beryllium
NASA Astrophysics Data System (ADS)
Using a variational method with an explicitly correlated Gaussian basis, we study the e+-Li and e+-Be complexes in the ground and lowest excited states with higher spin multiplicity. Our calculations provide rigorous theoretical confirmation that a positron can be attached to the excited states: 1s2s2pPo4 and 1s22s2pPo3 for e+-Li and e+-Be, respectively. The result is particularly notable for the e+-Be complex, as the excited Po3 state lies below the autoionization threshold. We report accurate binding energies, annihilation rates and structural properties of these positron-atom systems. The existence of the ground and metastable excited states with bound positron opens up a new route to the presently lacking experimental verification of stability of a positron binding to any neutral atom.
Bubin, Sergiy; Prezhdo, Oleg V.
Excitation with Effective Subcycle Laser Pulses
NASA Astrophysics Data System (ADS)
We have used laser pulses with a temporally shaped polarization to demonstrate the multiphoton excitation of the xenon 5g state within a subcycle of a laser pulse. Our polarization gated laser pulses are composed of circularly polarized sections at the leading and trailing edges of the pulse and of an experimentally defined linearly polarized central part. Only the linear part (the gate) of the pulse can excite neutral xenon in the 5g state. The transition cannot be driven with circularly polarized light because the number of photons needed would cause a violation of selection rules for the change of the magnetic quantum number. We show that the linearly polarized central part can be reduced to a subcycle pulse. This allows us to study excitation with an effective pulse as short as 2.3 fs at 800 nm. Electron imaging spectroscopy has been used to visualize the presence of excited states as a function of the pulse duration of the gate.
Marceau, C.; Gingras, G.; Witzel, B.
Excited State Intramolecular Proton Transfer in Polymers.
National Technical Information Service (NTIS)
Excited state intramolecular proton transfer (ESIPT) has been demonstrated in new intramoleculary hydrogen bonded (IHB) polymers of interest as photostabilizers, triplet quenchers, photochromic materials, laser dyes and electroluminescent materials. The n...
R. M. Tarkka S. A. Jenekhe
Code of Federal Regulations, 2010 CFR
...ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3...may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type...
Code of Federal Regulations, 2010 CFR
...ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3...may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type...
Code of Federal Regulations, 2013 CFR
...ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3...may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type...
Exciting dark matter in the Galactic Center
We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the Galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into e{sup +}e{sup -} and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.
Chen Fang; Cline, James M.; Fradette, Anthony; Frey, Andrew R.; Rabideau, Charles [Physics Department, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)
Chemical Bonding in Excited Electronic States.
National Technical Information Service (NTIS)
The electronic and vibrational spectra of the series of compounds fluorene, dibenzofuran (diphenylene oxide) and carbazole were examined for the purpose of studying chemical bonding in electronically excited molecules. Assignments of the ground state vibr...
S. C. Wait
We propose initial conditions that could facilitate the excitation of rogue waves. Understanding the initial conditions that foster rogue waves could be useful both in attempts to avoid them by seafarers and in generating highly energetic pulses in optical fibers.
Akhmediev, N.; Ankiewicz, A. [Optical Sciences Group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Soto-Crespo, J. M. [Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain)
Nonlinear excited waves on the interventricular septum
NASA Astrophysics Data System (ADS)
Using a novel ultrasonic noninvasive imaging method, we observe some phase singularities in propagating excited waves on a human cardiac interventricular septum (IVS) for a healthy young male. We present a possible physical model explaining one-dimensional dynamics of phase singularities in nonlinearly excited waves on the IVS. We show that at least one of the observed phase singularities in the excited waves on the IVS can be explained by the Bekki-Nozaki hole solution of the complex Ginzburg-Landau equation without any adjustable parameters. We conclude that the complex Ginzburg-Landau equation is such a suitable model for one-dimensional dynamics of cardiac phase singularities in nonlinearly excited waves on the IVS.
Bekki, Naoaki; Harada, Yoshifumi; Kanai, Hiroshi
Acoustics of Excited Jets: A Historical Perspective
NASA Technical Reports Server (NTRS)
The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.
Brown, Cliffard A.
Mode Selective Excitation Using Coherent Control Spectroscopy
Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.
Singh, Ajay K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India); School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Konradi, Jakow; Materny, Arnulf [School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Sarkar, Sisir K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India)
Sound from Turbulent Boundary Layer Excited Panels.
National Technical Information Service (NTIS)
The acoustic power radiated by thin flexible panels excited by turbulent boundary layer pressure fluctuations is estimated using a modal analysis, light fluid loading effects being included. Previous estimates of the modal radiation coefficients are impro...
H. G. Davies
Electron impact excitation cross sections for CO
The R-matrix method has been used to calculate electron impact excitation cross sections for the lowest seven electronically excited states of CO in the energy range 6-18 eV. These states are represented using configuration interaction (CI) expansions and an algorithm for treating long CI expansions in scattering calculations is presented. The calculations are carried out for a range of internuclear
L. A. Morgan; J. Tennyson
Electron impact excitation cross sections for phosphorus
: ��An analytic atomic independent-particle-model is used to generate wave functions for the valence and excited states of the\\u000a neutral phosphorus atom. These wave functions are used to calculate generalized oscillator strengths, and from these quantities\\u000a the cross sections are obtained in Born approximation. Various excitations from the ground state are considered, and results are presented for electron impact energies
P. S. Ganas
Synchrotron-excited luminescence of natural zircon
The luminescence properties of two single zircon crystals from kimberlite of Yakutia have been studied, excited by the DORIS\\u000a HASYLAB synchrotron, Germany, within energy range from the visible to the soft X-ray region (5�25, 50�200, and 500�620 eV)\\u000a at temperatures of 300 and 10 K. The luminescence spectra in the range of 2.5 to 6.0 eV and excitation spectra of
Yu. V. Shchapova; S. L. Votyakov; V. Yu. Ivanov; V. A. Pustovarov
Search for excited leptons at LEP
Excited leptons have been searched for using data recorded by the OPAL detector at LEP. No evidence for such particles has been found. From the study of e+e- --> l+l-gammagamma events, lower limits on the masses of spin-1\\/2 excited leptons are found to be 44.9 GeV at 95% confidence level. From the study of e+e- -->l+l-gamma events, upper limits on
M. Z. Akrawy; Gideon Alexander; J. Allison; P. P. Allport; K. J. Anderson; J. C. Armitage; Geoffrey T J Arnison; P. Ashton; Georges Azuelos; J. T. M. Baines; A. H. Ball; J. Banks; G. J. Barker; R. J. Barlow; J Richard Batley; J. Becker; T. Behnke; K. W. Bell; G. Bella; Siegfried Bethke; O. Biebel; U. Binder; Ian J Bloodworth; P. Bock; Horst Breuker; R. M. Brown; R. Brun; A. Buijs; Helfried J Burckhart; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; J. T. M. Chrin; I. Cohen; W. J. Collins; J. E. Conboy; M. Couch; M. Coupland; M. Cuffiani; S. Dado; G. M. Dallavalle; P. Debu; M. M. Deninno; A. Dieckmann; Michael Dittmar; M. S. Dixit; E. Duchovni; I. P. Duerdoth; D J P Dumas; H. El Mamouni; P. A. Elcombe; P. G. Estabrooks; E. Etzion; Franco Luigi Fabbri; Philippe Farthouat; H. M. Fischer; D. G. Fong; M. T. French; C. Fukunaga; A. Gaidot; O. Ganel; J. W. Gary; J. Gascon; N. I. Geddes; C. N. P. Gee; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; G. Giacomelli; V. Gibson; W. R. Gibson; James D Gillies; J. Goldberg; M. J. Goodrick; W. Gorn; D. Granite; E. Gross; P. Grosse-Wiesmann; Jacob Grunhaus; H. Hagedorn; J. Hagemann; M. Hansroul; C. K. Hargrove; J. Hart; P. M. Hattersley; M. Hauschild; C. M. Hawkes; E. Heflin; Richard J Hemingway; R. D. Heuer; J. C. Hill; S. J. Hillier; C. Ho; J. D. Hobbs; P. R. Hobson; D. Hochman; B. Holl; R James Homer; S. R. Hou; C. P. Howarth; R. E. Hughes-Jones; P. Igo-Kemenes; H. Ihssen; D. C. Imrie; A. Jawahery; P. W. Jeffreys; H. Jeremie; Martin Paul Jimack; M. Jobes; R. W. L. Jones; P. Jovanovic; D A Karlen; K. Kawagoe; T. Kawamoto; R. G. Kellogg; B. W. Kennedy; C. Kleinwort; D. E. Klem; G. Knop; T. Kobayashi; T. P. Kokott; L. K�pke; R V Kowalewski; H. Kreutzmann; J. von Krogh; J. Kroll; M. Kuwano; P. Kyberd; G. D. Lafferty; F. Lamarche; W. J. Larson; J. G. Layter; P. Le Du; P. Leblanc; A. M. Lee; Daniel Lellouch; P. Lennert; L. Lessard; L. Levinson; S. L. Lloyd; F. K. Loebinger; J. M. Lorah; B. Lorazo; Michael J Losty; J. Ludwig; N. Lupu; J. Ma; A. A. MacBeth; M. Mannelli; S. Marcellini; G. Maringer; A. J. Martin; J. P. Martin; T. Mashimo; P. M�ttig; U. Maur; T. J. McMahon; A. C. McPherson; F. Meijers; D. Menszner; F. S. Merritt; H. Mes; Aldo Michelini; R. P. Middleton; G. Mikenberg; D. J. Miller; C. Milstene; M. Minowa; W. Mohr; A. Montanari; T. Mori; M. W. Moss; P. G. Murphy; W. J. Murray; B. Nellen; H. H. Nguyen; M. Nozaki; A. J. P. O'Dowd; S. W. O'Neale; B. P. O'Neill; F. G. Oakham; F. Odorici; M. Ogg; H. Oh; M. J. Oreglia; S. Orito; J. P. Pansart; G. N. Patrick; S. J. Pawley; P. Pfister; J. E. Pilcher; James L Pinfold; D. E. Plane; B. Poli; A. Pouladdej; T. W. Pritchard; G. Quast; J. Raab; M. W. Redmond; D. L. Rees; M. Regimbald; K. Riles; C. M. Roach; S. A. Robins; A. Rollnik; J. M. Roney; S. Rossberg; A. M. Rossi; P. Routenburg; K. Runge; O. Runolfsson; S. Sanghera; R. A. Sansum; M. Sasaki; B. J. Saunders; A. D. Schaile; W. Schappert; P. Scharff-Hansen; H. von der Schmitt; S. Schreiber; J. Schwarz; A. Shapira; B. C. Shen; P. Sherwood; A. Simon; P. Singh; G. P. Siroli; A M Smith; A. M. Smith; T. J. Smith; G. A. Snow; E. J. Spreadbury; R. W. Springer; M. Sproston; K. Stephens; H. E. Stier; R. Str�hmer; D. Strom; H. Takeda; T. Takeshita; T. Tsukamoto; M. F. Turner; G. Tysarczyk-Niemeyer; D. van den Plas; G. J. Vandalen; G. Vasseur; C. J. Virtue; A. Wagner; C. Wahl; C. P. Ward; D. R. Ward; J. Waterhouse; P. M. Watkins; A. T. Watson; N. K. Watson; M. Weber; S. Weisz; N. Wermes; M. Weymann; G. W. Wilson; J. A. Wilson; I Wingerter-Seez; V.-H. Winterer; N. C. Wood; S A Wotton; B. Wuensch; T. R. Wyatt; R. Yaari; Y. Yang; G. Yekutieli; T. Yoshida; W. Zeuner; G. T. Zorn
Electron-impact vibrational excitation of tetrahydrofuran
NASA Astrophysics Data System (ADS)
Low-energy differential and integral cross sections for the electron-impact vibrational excitation of tetrahydrofuran are presented. The data concern four features in the vibrational excitation electron energy-loss spectrum of tetrahydrofuran over the energy-loss range of 0-0.9 eV. The results show weak influence from long-range dipole interactions, being mainly isotropic. Comparison with earlier work is presented.
Khakoo, M. A.; Orton, D.; Hargreaves, L. R.; Meyer, N.
Coulomb excitation of radioactive 20, 21 Na
The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ? 5�106 ions\\/s were accelerated to 1.7MeV\\/A and Coulomb excited in a 0.5mg\\/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for -ray detection, while scattered nuclei were observed by
M. A. Schumaker; D. Cline; G. Hackman; C. Pearson; C. E. Svensson; C. Y. Wu; A. Andreyev; R. A. E. Austin; G. C. Ball; D. Bandyopadhyay; J. A. Becker; A. J. Boston; H. C. Boston; L. Buchmann; R. Churchman; F. Cifarelli; R. J. Cooper; D. S. Cross; D. Dashdorj; G. A. Demand; M. R. Dimmock; T. E. Drake; P. Finlay; A. T. Gallant; P. E. Garrett; K. L. Green; A. N. Grint; G. F. Grinyer; L. J. Harkness; A. B. Hayes; R. Kanungo; A. F. Lisetskiy; K. G. Leach; G. Lee; R. Maharaj; J. P. Martin; F. Moisan; A. C. Morton; S. Mythili; L. Nelson; O. Newman; P. J. Nolan; J. N. Orce; E. Padilla-Rodal; A. A. Phillips; M. Porter-Peden; J. J. Ressler; R. Roy; C. Ruiz; F. Sarazin; D. P. Scraggs; J. C. Waddington; J. M. Wan; A. Whitbeck; S. J. Williams; J. Wong
Periodic acceptor excitation spectroscopy of single molecules
Alternating-laser excitation (ALEX) spectroscopy has recently been added to the single-molecule spectroscopy toolkit. ALEX\\u000a monitors interaction and stoichiometry of biomolecules, reports on biomolecular structure by measuring accurate F�rster resonance\\u000a energy transfer (FRET) efficiencies, and allows sorting of subpopulations on the basis of stoichiometry and FRET. Here, we\\u000a demonstrate that a simple combination of one continuous-wave donor-excitation laser and one directly
S�ren Doose; Mike Heilemann; Xavier Michalet; Shimon Weiss; Achillefs N. Kapanidis
Chromatic two-photon excitation fluorescence imaging.
We report on a chromatic axial scanning method for two-photon excitation fluorescence imaging. Effective axial scanning is achieved by incorporating a Fresnel lens in the system, which has large chromatic aberration and can therefore focus the excitation beam to different axial positions depending on its wavelength. We experimentally demonstrated this technique and used it to image the cross-section of fluorescent microspheres. PMID:19566629
Xu, Q; Shi, K; Yin, S; Liu, Z
Fast pulsed excitation wiggler or undulator
A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.
van Steenbergen, Arie (Shoreham, NY)
Search for excited neutrinos at HERA
We present a search for excited neutrinos using e?p data taken by the H1 experiment at HERA at a center-of-mass energy of 318�GeV with an integrated luminosity of 15�pb?1. No evidence for excited neutrino production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, f\\/?, independently of the relative couplings to
C. Adloff; V. Andreev; B. Andrieu; T. Anthonis; V. Arkadov; A. Astvatsatourov; A. Babaev; J. B�hr; P. Baranov; E. Barrelet; W. Bartel; P. Bate; J. Becker; A. Beglarian; O. Behnke; C. Beier; A. Belousov; T. Benisch; Ch. Berger; T. Berndt; J. C. Bizot; J. Boehme; V. Boudry; W. Braunschweig; V. Brisson; H.-B. Br�ker; D. P. Brown; W. Br�ckner; D. Bruncko; J. B�rger; F. W. B�sser; A. Bunyatyan; G. Buschhorn; L. Bystritskaya; A. J. Campbell; S. Caron; F. Cassol-Brunner; D. Clarke; B. Clerbaux; C. Collard; J. G. Contreras; Y. R. Coppens; J. A. Coughlan; M.-C. Cousinou; B. E. Cox; G. Cozzika; J. Cvach; J. B. Dainton; W. D. Dau; K. Daum; M. Davidsson; B. Delcourt; N. Delerue; R. Demirchyan; C. Diaconu; J. Dingfelder; P. Dixon; V. Dodonov; J. D. Dowell; A. Droutskoi; C. Duprel; G. Eckerlin; D. Eckstein; V. Efremenko; S. Egli; R. Eichler; F. Eisele; E. Eisenhandler; M. Ellerbrock; E. Elsen; M. Erdmann; W. Erdmann; P. J. W. Faulkner; L. Favart; A. Fedotov; R. Felst; J. Ferencei; S. Ferron; M. Fleischer; Y. H. Fleming; G. Fl�gge; A. Fomenko; I. Foresti; J. Form�nek; G. Franke; E. Gabathuler; K. Gabathuler; J. Garvey; J. Gassner; R. Gerhards; C. Gerlich; S. Ghazaryan; L. Goerlich; N. Gogitidze; M. Goldberg; C. Grab; H. Gr�ssler; T. Greenshaw; G. Grindhammer; T. Hadig; D. Haidt; L. Hajduk; J. Haller; W. J. Haynes; B. Heinemann; G. Heinzelmann; R. C. W. Henderson; S. Hengstmann; H. Henschel; R. Heremans; G. Herrera; I. Herynek; M. Hildebrandt; K. H. Hiller; J. Hladk�; P. H�ting; D. Hoffmann; R. Horisberger; S. Hurling; M. Ibbotson; �. ??sever; M. Jacquet; L. Janauschek; X. Janssen; V. Jemanov; L. J�nsson; C. Johnson; D. P. Johnson; M. A. S. Jones; H. Jung; D. Kant; M. Kapichine; O. Karschnick; F. Keil; N. Keller; J. Kennedy; I. R. Kenyon; S. Kermiche; C. Kiesling; P. Kjellberg; M. Klein; C. Kleinwort; T. Kluge; G. Knies; B. Koblitz; S. D. Kolya; V. Korbel; P. Kostka; S. K. Kotelnikov; R. Koutouev; A. Koutov; H. Krehbiel; J. Kroseberg; K. Kr�ger; A. K�pper; T. Kuhr; T. Kur?a; R. Lahmann; D. Lamb; M. P. J. Landon; W. Lange; T. La�tovi?ka; P. Laycock; E. Lebailly; A. Lebedev; B. Lei�ner; R. Lemrani; V. Lendermann; S. Levonian; M. Lindstroem; B. List; E. Lobodzinska; B. Lobodzinski; A. Loginov; N. Loktionova; V. Lubimov; S. L�ders; D. L�ke; L. Lytkin; H. Mahlke-Kr�ger; N. Malden; E. Malinovski; I. Malinovski; R. Mara?ek; P. Marage; J. Marks; R. Marshall; H.-U. Martyn; J. Martyniak; S. J. Maxfield; D. Meer; A. Mehta; K. Meier; A. B. Meyer; H. Meyer; J. Meyer; P.-O. Meyer; S. Mikocki; D. Milstead; T. Mkrtchyan; R. Mohr; S. Mohrdieck; M. N. Mondragon; F. Moreau; A. Morozov; J. V. Morris; K. M�ller; P. Mur??n; V. Nagovizin; B. Naroska; J. Naumann; Th. Naumann; G. Nellen; P. R. Newman; T. C. Nicholls; F. Niebergall; C. Niebuhr; O. Nix; G. Nowak; J. E. Olsson; D. Ozerov; V. Panassik; C. Pascaud; G. D. Patel; M. Peez; E. Perez; J. P. Phillips; D. Pitzl; R. P�schl; I. Potachnikova; B. Povh; K. Rabbertz; G. R�del; J. Rauschenberger; P. Reimer; B. Reisert; D. Reyna; C. Risler; E. Rizvi; P. Robmann; R. Roosen; A. Rostovtsev; S. Rusakov; K. Rybicki; D. P. C. Sankey; J. Scheins; F.-P. Schilling; D. Schmidt; S. Schmidt; M. Schneider; L. Schoeffel; A. Sch�ning; T. Sch�rner; V. Schr�der; H.-C. Schultz-Coulon; K. Sedl�k; F. Sefkow; V. Shekelyan; I. Sheviakov; L. N. Shtarkov; Y. Sirois; T. Sloan; P. Smirnov; Y. Soloviev; D. South; V. Spaskov; A. Specka; H. Spitzer; R. Stamen; B. Stella; J. Stiewe; U. Straumann; M. Swart; M. Ta�evsk�; V. Tchernyshov; S. Tchetchelnitski; G. Thompson; P. D. Thompson; N. Tobien; D. Traynor; P. Tru�l; G. Tsipolitis; I. Tsurin; J. Turnau; J. E. Turney; E. Tzamariudaki; S. Udluft; M. Urban; A. Usik; S. Valk�r; A. Valk�rov�; C. Vall�e; S. Vassiliev; Y. Vazdik; A. Vichnevski; K. Wacker; R. Wallny; B. Waugh; G. Weber; M. Weber; D. Wegener; C. Werner; M. Werner; N. Werner; G. White; S. Wiesand; T. Wilksen; M. Winde; G.-G. Winter; Ch. Wissing; M. Wobisch; E.-E. Woehrling; A. C. Wyatt; J. ��?ek; J. Z�le��k; Z. Zhang; A. Zhokin; F. Zomer; J. Zsembery; M. zur Nedden
High Frequency Electromechanical Imaging of Ferroelectrics in a Liquid Environment
The coupling between electrical and mechanical phenomena is a ubiquitous feature of many information and energy storage materials and devices. In addition to involvement in performance and degradation mechanisms, electromechanical effects underpin a broad spectrum of nanoscale imaging and spectroscopies including piezoresponse force and electrochemical strain microscopies. Traditionally, these studies are conducted under ambient conditions. However, applications related to imaging energy storage and electrophysiological phenomena require operation in a liquid phase and therefore the development of electromechanical probing techniques suitable to liquid environments. Due to the relative high conductivity of most liquids and liquid decomposition at low voltages, the transfer of characterization techniques from ambient to liquid is not straightforward. Here we present a detailed study of ferroelectric domain imaging and manipulation in thin film BiFeO{sub 3} using piezoresponse force microscopy in liquid environments as model systems for electromechanical phenomena in general. We explore the use of contact resonance enhancement and the application of multifrequency excitation and detection principles to overcome the experimental problems introduced by a liquid environment. Understanding electromechanical sample characterization in liquid is a key aspect not only for ferroelectric oxides but also for biological and electrochemical sample systems.
Jesse, Stephen [ORNL; Chu, Ying-Hao [National Chiao Tung University, Hsinchu, Taiwan; Kalinin, Sergei V [ORNL
Redox chemistry at liquid\\/liquid interfaces
The interface between two immiscible liquids with immobilized photosynthetic pigments can serve as the simplest model of a\\u000a biological membrane convenient for the investigation of photoprocesses accompanied by spatial separation of charges. As it\\u000a follows from thermodynamics, if the resolvation energies of substrates and products are very different, the interface between\\u000a two immiscible liquids may act as a catalyst. Theoretical
A. G. Volkov; D. W. Deamer
Liquid Crystal Materials and Liquid Crystal Displays
Since the early 1970s, three major prerequisites have brought the success of the liquid crystal display (LCD) technology to its key role of today. Namely, the discovery of electro-optical field-effects on which the displays are based, the successful search for liquid crystals (LCs) with material properties that meet the complex requirements of electro-optical effects and render the effects applicable in
Martin Schadt
Excited state dynamics of phthalocyanine films
Femtosecond pump-probe transient absorption measurements were performed for thermally evaporated polycrystalline vanadyl and lead phthalocyanine (VOPc and PbPc) films in order to obtain information about the excitation energy migration and relaxation. The films were shown to be composed of phase II and amorphous material. Fast excitation localization in phase II was concluded from measurement and analysis of the ground and excited state spectra. Comparison of the ground state, difference absorption, and luminescence spectra suggests a small oscillator strength of the electronic transition from the lowest excited state to the ground state. The influence of local heating on the transient spectra is discussed, and the possibility to obtain the excitation decay kinetics free from this influence is proposed. Exciton-exciton annihilation with a time dependent rate (proportional to t{sup -0.5}) is observed in both films. This is explained by one-dimensional diffusion-limited annihilation. Linear relaxation times are equal to 28{+-}6 and 42{+-}8 ps and approximate intermolecular excitation hopping times of 0.1 divide 0.4 and 0.02 divide 0.08 ps were determined for VOPc and PbPc, respectively. 22 refs., 8 figs., 1 tab.
Gulbians, V.; Valkunas, L. [Vilnius Inst. of Physics (Lithuania)] [Vilnius Inst. of Physics (Lithuania); Chachisvillis, M.; Sundstrom, V. [Lund Univ. (Sweden)] [Lund Univ. (Sweden)
Development of Dual Quartz Sensor for Liquid Analysis
NASA Astrophysics Data System (ADS)
A dual quartz sensor has been developed which enables the analyses of physicochemical properties of liquids. In this sensor, an ACR (Antiparallel Coupled Resonator) type quartz sensor and a LFE (Lateral Field Excited) type quartz sensor were fabricated on a same plate. The ACR can measure frequency response caused by a mechanical characteristic (viscoelasticity) of liquids. The LFE can measure frequency response caused by both the mechanical characteristic and the electrical characteristics (conductivity and dielectric constant) of liquids. By subtracting the frequency shift of the LFE and the ACR, the dual quartz sensor is possible to calculate the electrical characteristics. Therefore the dual quartz sensor allowed simultaneous measurements of electrical characteristics and the mechanical characteristic of a liquid.
Takeishi, Taichi; Emura, Keito; Abe, Takashi
Excess dielectron in an ionic liquid as a dynamic bipolaron.
We report an ab initio molecular dynamics simulation study on the accommodation of a dielectron in a pyridinium ionic liquid in both the singlet and triplet state. In contrast to water and liquid ammonia, a dielectron does not prefer to reside in cavity-shaped structures in the ionic liquid. Instead, it prefers to be distributed over more cations, with long-lived diffuse and short-lived localized distributions, and with a triplet ground state and a low-lying, open-shell singlet excited state. The two electrons evolve nonsynchronously in both states via a diffuse-versus-localized interconversion mechanism that features a dynamic bipolaron with a modest mobility, slightly lower than a hydrated electron. This work presents the first detailed study on the structures and dynamics of a dielectron in ionic liquids. PMID:23521297
Liu, Jinxiang; Wang, Zhiping; Zhang, Meng; Cukier, Robert I; Bu, Yuxiang
Excess Dielectron in an Ionic Liquid as a Dynamic Bipolaron
NASA Astrophysics Data System (ADS)
We report an ab initio molecular dynamics simulation study on the accommodation of a dielectron in a pyridinium ionic liquid in both the singlet and triplet state. In contrast to water and liquid ammonia, a dielectron does not prefer to reside in cavity-shaped structures in the ionic liquid. Instead, it prefers to be distributed over more cations, with long-lived diffuse and short-lived localized distributions, and with a triplet ground state and a low-lying, open-shell singlet excited state. The two electrons evolve nonsynchronously in both states via a diffuse-versus-localized interconversion mechanism that features a dynamic bipolaron with a modest mobility, slightly lower than a hydrated electron. This work presents the first detailed study on the structures and dynamics of a dielectron in ionic liquids.
Liu, Jinxiang; Wang, Zhiping; Zhang, Meng; Cukier, Robert I.; Bu, Yuxiang
Liquid-crystalline nanoparticles: Hybrid design and mesophase structures.
Liquid-crystalline nanoparticles represent an exciting class of new materials for a variety of potential applications. By combining supramolecular ordering with the fluid properties of the liquid-crystalline state, these materials offer the possibility to organise nanoparticles into addressable 2-D and 3-D arrangements exhibiting high processability and self-healing properties. Herein, we review the developments in the field of discrete thermotropic liquid-crystalline nanoparticle hybrids, with special emphasis on the relationship between the nanoparticle morphology and the nature of the organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed. PMID:22509204
Nealon, Gareth L; Greget, Romain; Dominguez, Cristina; Nagy, Zsuzsanna T; Guillon, Daniel; Gallani, Jean-Louis; Donnio, Bertrand
Charge transfer reactions in nematic liquid crystals
NASA Astrophysics Data System (ADS)
Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4'-(n-pentyl)-4- cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. We show that excited state charge separation is non-adiabatic, and obtain the unexpected result that charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains relative to the orientation of PNI+-PI-. We also report the result of time resolved electron paramagnetic resonance studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increase from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.
Wiederrecht, Gary P.; Wasielewski, Michael R.; Galili, Tamar; Levanon, Haim
Theory of quantum impurities in spin liquids
NASA Astrophysics Data System (ADS)
We describe spin correlations in the vicinity of a generalized impurity in a wide class of fractionalized spin liquid states. We argue that the primary characterization of the impurity is its electric charge under the gauge field describing singlet excitations in the spin liquid. We focus on two gapless U(1) spin liquids described by (2+1) -dimensional conformal field theories (CFT): the staggered flux (sF) spin liquid, and the deconfined critical point between the N�el and valence-bond-solid (VBS) states. In these cases, the electric charge is argued to be an exactly marginal perturbation of the CFT. Consequently, the impurity susceptibility has a 1/T temperature dependence, with an anomalous Curie constant, which is a universal number associated with the CFT. One unexpected feature of the CFT of the sF state is that an applied magnetic field does not induce any staggered spin polarization in the vicinity of the impurity (while such a staggered magnetization is present for the N�el-VBS case). These results differ significantly from earlier theories of vacancies in the sF state, and we explicitly demonstrate how our gauge theory corrects these works. We discuss implications of our results for the cuprate superconductors, organic Mott insulators, and graphene.
Kolezhuk, Alexei; Sachdev, Subir; Biswas, Rudro R.; Chen, Peiqiu
Mechanical models for tanks containing two liquids
The well-known Housner`s mechanical model for laterally excited rigid tanks that contain one liquid is generalized to permit consideration of tanks that contain two liquids under the horizontal and rocking base motions. Two mechanical models are developed herein; one is for rigid tanks and the other for flexible tanks. The model for rigid tanks has a rigidly attached mass and infinite number of elastically supported masses. The rigid attached mass which possesses a mass moment of inertia represents the impulsive component, whereas the elastically supported masses which do not possess mass moment of inertia represent the convective component of the response. These masses and their heights are chosen such that, under the same base motions, the base shear and base moments of the model match those of the original liquid-tank system. The spring stiffness constants for the elastically supported masses in the model are determined from the sloshing frequencies of the liquid-tank system. The model for flexible tanks, however, only represents the impulsive action of the hydrodynamic response. It has an elastically supported mass that does not possess mass moment of inertia and a member that has no mass but possesses a mass moment of inertia. This latter model is proposed for the study of the effect of the soil-structure interaction.
Tang, Y.
Fluorescence response of coumarin-153 in N-alkyl-N-methylmorpholinium ionic liquids: are these media more structured than the imidazolium ionic liquids?
The fluorescence behavior of coumarin-153 (C153) has been studied in four N-alkyl-N-methylmorpholinium ionic liquids differing in the alkyl chain length attached to the N-methylmorpholinium cation as a function of the excitation wavelength and temperature to understand some of the physicochemical characteristics of these largely unexplored ionic liquids. While the polarity of the ionic liquid with the smallest alkyl chain length is found comparable to that of the commonly used imidazolium ionic liquids, the probe molecule experiences a less polar environment with increasing chain length of the alkyl group attached to the morpholinium cation. The room temperature steady-state fluorescence spectrum of C153 in these solvents is found to be dependent on the excitation wavelength, and this effect is most pronounced in long chain containing ionic liquids. A bathochromic shift of the fluorescence maximum is observed at higher temperature. The excitation wavelength and temperature dependence of the fluorescence of C153 is explained considering a domain structure of these ionic liquids. The time-resolved fluorescence anisotropy measurements indicate the microviscosity around the probe molecule to be significantly different from the bulk viscosity of the long-chain ionic liquids. The solvent reorganization dynamics, as studied by monitoring the time-dependent fluorescence Stokes shift of C153 in these ionic liquids, is found to be slow and similar to that in imidazolium ionic liquids. The time-resolved measurements under isoviscous conditions seem to provide additional support to the organized domain structure of these ionic liquids. PMID:23083398
Khara, Dinesh Chandra; Samanta, Anunay
Fluorescence Spectrum and Decay Measurement for Hsil VS Normal Cytology Differentiation in Liquid Pap Smear Supernatant
NASA Astrophysics Data System (ADS)
Cervical smear material contains endo and exocervical cells, mucus and inflammative, immune cells in cases of pathology. Just not destroyed keratinocytes lay on the glass for microscopy. Liquid cytology supernatant apart other diagnostics could be used for photodiagnostic. The spectroscopic parameters suitable for Normal and HSIL cytology groups supernatant differentiation are demonstrated. The dried liquid PAP supernatant fractions-sediment and liquid were investigated. Excitation and emission matrices (EEM), supernatant fluorescence decay measured under 280 nm diode short pulse excitation and fluorescence spectroscopy by excitation with 355 nm laser light were analyzed. The differences between Normal and HSIL groups were statistically proven in the certain spectral regions. Fluorescence decay peculiarities show spectral regions consisting of few fluorophores. Obtained results on fluorescence differences in Normal and HSIL groups' supernatant shows the potency of photodiagnosis application in cervical screening.
Vaitkuviene, A.; Gegzna, V.; Juodkazis, S.; Jursenas, S.; Miasojedovas, S.; Kurtinaitiene, R.; Rimiene, J.; Vaitkus, J.
Excitation Mechanisms of RE Ions in Semiconductors
NASA Astrophysics Data System (ADS)
This chapter presents an overview of the mechanisms responsible for the excitation of optically active rare-earth (RE) ions in semiconductors. Besides resonant excitation of the RE 4f shell, several non-resonant processes can take place in which the host is excited first. These indirect mechanisms involve nonradiative transfer of the recombination energy of electrons and holes to nearby RE ions. Distinct excitation processes arise because of the various conditions under which the electron may recombine with a hole. The different possibilities are presented and discussed in the first part of this chapter. Carriers of opposite charge bind to each other to form either a free exciton or a trapped (bound) exciton. In the latter case, the trapping can arise from the incorporation of RE ions which induces distortions of the host lattice. The exciton trapping can also be due to an impurity, a local defect or even an extended defect. Other possible mechanisms involve the capture of an electron by the 5d shell changing the valence state from trivalent to divalent with the subsequent capture of a hole. Finally, the role of impurities associated with donor-acceptor pairs in the recombination of electrons and holes with energy transfer to RE ions is discussed. In the second part of this chapter the specific case of RE-doped GaN is considered. Results are presented to show that local defects play a major role in the excitation process by binding excitons with a subsequent energy transfer to RE ions. A general modelling of the RE excitation mechanism mediated by bound excitons (BE) is presented and discussed. Finally, experiments using two excitation sources are shown to give valuable information concerning the RE-related defects.
Braud, Alain
Electronic excitations in long polyenes revisited
NASA Astrophysics Data System (ADS)
We apply the valence shell model OM2 [W. Weber and W. Thiel, Theor. Chem. Acc. 103, 495, (2000)] combined with multireference configuration interaction (MRCI) to compute the vertical excitation energies and transition dipole moments of the low-energy singlet excitations in the polyenes with 4 <= N <= 22?-electrons. We find that the OM2/MRCI descriptions closely resemble those of Pariser-Parr-Pople (PPP) ?-electron models [P. Tavan and K. Schulten, Phys. Rev. B 36, 4337, (1987)], if equivalent MRCI procedures and regularly alternating model geometries are used. OM2/MRCI optimized geometries are shown to entail improved descriptions particularly for smaller polyenes (N <= 12), for which sizeable deviations from the regular model geometries are found. With configuration interaction active spaces covering also the ?- in addition to the ?-electrons, OM2/MRCI excitation energies turn out to become smaller by at most 0.35 eV for the ionic and 0.15 eV for the covalent excitations. The particle-hole (ph) symmetry, which in Pariser-Parr-Pople models arises from the zero-differential overlap approximation, is demonstrated to be only weakly broken in OM2 such that the oscillator strengths of the covalent 1Bu- states, which artificially vanish in ph-symmetric models, are predicted to be very small. According to OM2/MRCI and experimental data the 1Bu- state is the third excited singlet state for N < 12 and becomes the second for N >= 14. By comparisons with results of other theoretical approaches and experimental evidence we argue that deficiencies of the particular MRCI method employed by us, which show up in a poor size consistency of the covalent excitations for N > 12, are caused by its restriction to at most doubly excited references.
Schmidt, Maximilian; Tavan, Paul
Determination of MDMA, MDA, MDEA and MBDB in oral fluid using high performance liquid chromatography with native fluorescence detection
This paper describes the analytical methodology for the determination of MDMA, MDA, MDEA and MBDB in oral fluid. After a liquid�liquid extraction, the analysis was carried out by high performance liquid chromatography (HPLC), with fluorescence detection. The detector wavelength was fixed at 285nm for excitation and 320nm for emission. The mobile phase, a mixture of phosphate buffer (pH=5) and acetonitrile
Marta Concheiro; Ana de Castro; Oscar Quintela; Manuel L�pez-Rivadulla; Angelines Cruz
Monogroove liquid heat exchanger
NASA Technical Reports Server (NTRS)
A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).
Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)
A liquid level detector for conductive liquids for vertical installation in a tank, the detector having a probe positioned within a sheath and insulated therefrom by a seal so that the tip of the probe extends proximate to but not below the lower end of the sheath, the lower end terminating in a rim that is provided with notches, said lower end being tapered, the taper and notches preventing debris collection and bubble formation, said lower end when contacting liquid as it rises will form an airtight cavity defined by the liquid, the interior sheath wall, and the seal, the compression of air in the cavity preventing liquid from further entry into the sheath and contact with the seal. As a result, the liquid cannot deposit a film to form an electrical bridge across the seal.
Tshishiku, Eugene M. (Augusta, GA)
Surface waves on non-Newtonian viscoelastic liquids.
In the present work, we study the dynamics of thermally excited fluctuations on the surface of non-Newtonian viscoelastic liquids, which shows complex behaviors such as crossover between the capillary wave and the elastic wave, and the coexistence of several modes. We show that the power spectrum is separated into surface localized modes and the bulk shear modes, and they are decomposed further into several modes using the partial fraction expansion. The peak positions of these modes are characterized by roots of a polynomial equation. We calculate the decomposition of the surface wave spectra numerically, and discuss evolution of constituent peaks with liquid parameters. PMID:21517511
Ohmasa, Y; Yao, M
Terahertz/optical sum and difference frequency generation in liquids
NASA Astrophysics Data System (ADS)
A high-sensitivity setup for the observation of ?(2)-based, terahertz/optical, sum and difference frequency generation in liquids is presented. It relies on launching wavefront modulated terahertz radiation into a liquid traversed by an optical beam. Phase matching and polarization selection rules can be tuned to support three wave mixing via either chiral allowed electric dipole processes or higher order quadrupole/magnetic dipole processes. Under nonresonant excitation, hyperpolarizabilities from quadrupole/magnetic dipole processes are measured. Since this approach does not require terahertz transmission through macroscopic thicknesses of water, it has the potential to open a new window on the terahertz dynamics of water solvated molecules.
Feil, Thomas; Allen, S. J.
Collective microdynamics of liquid lithium: An inelastic neutron scattering study
NASA Astrophysics Data System (ADS)
A portion of the dispersion curve for collective modes in liquid lithium has been constructed from experimental data on inelastic scattering of slow neutrons obtained on the DIN-2PI neutron spectrometer (IBR-2 reactor, Joint Institute for Nuclear Research, Dubna, Russia). Measurements have been performed at a temperature of 500 K ( T m (Li) = 453.7 K). The coherent scattering component has been separated from the experimental spectra and analyzed. Information on the characteristics of collective excitations in liquid lithium has been derived.
Blagoveshchenski?, N. M.; Novikov, A. G.; Savostin, V. V.
Surface plasmon-enhanced lasing in dye-doped cholesteric liquid crystals.
This study shows the results of a photonic band-edge laser using dye-doped cholesteric liquid crystals (CLCs) combined with silver (Ag) nanoparticles. When the Ag nanoparticle surface plasmon resonance wavelength matched the excitation source wavelength, the large optical fields provided by surface plasmons increased the fluorescence of dye molecules by enhancing the molecular excitation rate, achieving a low lasing threshold and high pumping efficiency. PMID:23037118
Shih, Cheng-Yu; Yeh, Hui-Chen
Method for beam steering compensation in an ultra-high power liquid laser
Thermally induced distortion of the optical wavefront caused by heating of the laser media by waste heat from the excitation process and absorption of laser radiation creates optical phase errors. A system generates an error signal derived from the optical phase errors. The error signal is fed back to the power supplies driving semiconductor diodes that excite the lasing liquid thereby introducing an electrically controllable wedge into the optical cavity to correct the optical phase errors.
Ault, Earl R. (Livermore, CA)
Comparison of vapor formation of water at the solid/water interface to colloidal solutions using optically excited gold nanostructures.
The phase transformation properties of liquid water to vapor is characterized by optical excitation of the lithographically fabricated single gold nanowrenches and contrasted to the phase transformation properties of gold nanoparticles located and optically excited in a bulk solution system [two and three dimensions]. The 532 nm continuous wave excitation of a single gold nanowrench results in superheating of the water to the spinodal decomposition temperature of 580 � 20 K with bubble formation below the spinodal decomposition temperature being a rare event. Between the spinodal decomposition temperature and the boiling point liquid water is trapped into a metastable state because a barrier to vapor nucleation exists that must be overcome before the thermodynamically stable state is realized. The phase transformation for an optically heated single gold nanowrench is different from the phase transformation of optically excited colloidal gold nanoparticles solution where collective heating effects dominates and leads to the boiling of the solution exactly at the boiling point. In the solution case, the optically excited ensemble of nanoparticles collectively raises the ambient temperature of water to the boiling point where liquid is converted into vapor. The striking difference in the boiling properties of the single gold nanowrench and the nanoparticle solution system can be explained in terms of the vapor-nucleation mechanism, the volume of the overheated liquid, and the collective heating effect. The interpretation of the observed regimes of heating and vaporization is consistent with our theoretical modeling. In particular, we explain with our theory why the boiling with the collective heating in a solution requires 3 orders of magnitude less intensity compared to the case of optically driven single nanowrench. PMID:24476426
Baral, Susil; Green, Andrew J; Livshits, Maksim Y; Govorov, Alexander O; Richardson, Hugh H
Liquid capillary scintillation detectors
The authors have been developing liquid-in-capillary detectors for tracking applications in high energy physics experiments. The detectors consist of glass capillaries of low refractive index filled with liquids of sufficiently high refractive index to produce an efficient waveguides. This paper describes recent work in which scintillating core liquids were prepared from the solvent 1-phenylnaphthalene and single solutes of selected fluorescent dyes.
Puseljic, D.; Baumbaugh, B.; Ditmire, T.; Kennedy, C.; Ruchti, R.; Ryan, J. (Notre Dame Univ., IN (USA). Dept. of Physics); Baumbaugh, A.; Knickerbocker, K. (Collimated Holes, Inc., Campbell, CA (USA)); Ellis, J.; Mead, R.; Swanson, D. (Collimated Holes, Inc., Campbell, CA (USA))
Modification of liquid hydrocarbons
Improved rate of dissolution in liquid hydrocarbon fuels, of specified tert-butylstyrene copolymers capable of imparting anti-misting characteristics to the fuel, is obtained when the copolymer, following its production by aqueous emulsion polymerization of the monomers, is isolated from the resulting latex by a process of flocculation, separation, washing and drying at moderate temperatures. The copolymer thus isolated is advantageously incorporated in the liquid fuel in the form of a slurry with a hydroxylic liquid and an amine.
Roberts, T. S.; Waite, F. A.
The possibility of icosahedral order in liquids and its role in glass transition is discussed in a broad context of statistical mechanics of liquid. It is pointed out that the structures of glasses and liquids are described both in terms of the topology of atomic bond networks as well as the local distortion of the atomic bonds. While topology plays a dominant role in covalent glasses, local distortion is likely to be more important for metallic glasses.
Egami, Takeshi [ORNL
NASA Astrophysics Data System (ADS)
By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.
Vasdekis, A. E.; Cuennet, J. G.; Psaltis, D.
Ultrasonic liquid level detector
An ultrasonic liquid level detector for use within a shielded container, the detector being tubular in shape with a chamber at its lower end into which liquid from in the container may enter and exit, the chamber having an ultrasonic transmitter and receiver in its top wall and a reflector plate or target as its bottom wall whereby when liquid fills the chamber a complete medium is then present through which an ultrasonic wave may be transmitted and reflected from the target thus signaling that the liquid is at chamber level.
Kotz, Dennis M. (North Augusta, SC); Hinz, William R. (Augusta, GA)
Targeting individual excited states in DMRG.
NASA Astrophysics Data System (ADS)
The low-lying excited states of ?-conjugated molecules are important for the development of novel devices such as lasers, light-emitting diodes, photovoltaic cells, and field-effect transistors [1,2]. The ab-intio Density Matrix Renormalization Group (DMRG) provides a powerful way to explore the electronic structure of quasi-one-dimensional systems such as conjugated organic oligomers. However, DMRG is limited to targeting only low-lying excited states through state-averaged DMRG (SDMRG). There are several drawbacks; state-averaging degrades the accuracy of the excited states and is limited to at most a few of the low-lying states [3]. In this study, we present a new method for targeting higher individual excited states. Due to progress in the field of numerical analysis presented by Van Der Horst and others [4], we are able to target individual excited states of the Hamiltonian. This is accomplished by modifying the Jacobi-Davidson algorithm via a ``Harmonic Ritz'' procedure. We will present studies of oligoacenes and polyenes that compare the accuracy of SDMRG and Harmonic Davidson DMRG. [1] Burroughes, et al. , Nature 347, 539 (1990). [2] Shirota, J. Mater. Chem. 10, 1, (2000). [3] Ramasesha, Pati, Krishnamurthy, Shuai, Bredas, Phys. Rev. B. 54, 7598, (1997). [4] Bai, Demmel, Dongarra, Ruhe, Van Der Horst, Templates for the Solution of Algebraic Eigenvalue Problems, SIAM, 2000.
Dorando, Jonathan; Hachmann, Johannes; Kin-Lic Chan, Garnet
Core-excitation effects on atomic transitions
NASA Astrophysics Data System (ADS)
By including explicitly the electronic configurations with three simultaneously excited electronic orbitals, we have successfully extended the BSCI (B-spline based configuration interaction) method to estimate directly the effects of inner shell core-excitation to atomic transitions. In particular, we are able to carry out detailed ab initio investigation on the core polarization effects without the use of parameterized model potential. We investigate in detail quantitatively the change in atomic transition rate due to the core-excitations for four-electron systems, especially for transitions involving double excited states and those with small oscillator strengths. Quantitatively, for the Be-like systems, we are able to achieve an agreement between the length and velocity results to better than 1% for most transitions. Applications to neutral Carbon also demonstrate the effectiveness of the extended BSCI methods to treat explicitly the core-excitation in atomic transitions. A typical extended BSCI calculation requires substantially more computational effort than other L2 methods. It can only be carried out under the parallel computing environment. With the ongoing hardware upgrading from 32-bit to 64-bit computing environment, we anticipate a more comprehensive extended BSCI study on Carbon-like ions and heavier atomic systems with 2 closed shells such as Si-like ions in coming years.
Luo, Yuxiang