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Volume 21 Issue 10
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Original Articles
 Select Decay Rate of Energy Eigenfunctions in Classically Energetically Inaccessible Regions WANG Wen-Ge Chin. Phys. Lett. 2004, 21 (10): 1869-1872 .   Abstract   PDF(pc) (315KB) ( 564 ) Classically energetically inaccessible parts of energy eigenfunctions in configuration space are studied by making use of a generalization of Brillouin--Wigner perturbation theory. Approximate formulas are proposed for describing local decaying rate of this part of energy eigenfunctions, which are useful in the study of quantum phenomena,such as tunnelling effect, and are tested in an anharmonic oscillator.
 Select Asymptotic Tails of Massive Scalar Fields in a Stationary Axisymmetric EMDA Black Hole Geometry PAN Qi-Yuan, JING Ji-Liang Chin. Phys. Lett. 2004, 21 (10): 1873-1876 .   Abstract   PDF(pc) (230KB) ( 811 ) The late-time tail behaviour of massive scalar fields is studied analytically in a stationary axisymmetric Einstein-Maxwell Dilaton-Axion (EMDA) black hole geometry. It is shown that the asymptotic behaviour of massive perturbations is dominated by the oscillatory inverse power-law decaying tail t-(l+3/2)sin(μt) at the intermediate late times, and by the asymptotic tail t-5/6sin(μt) at asymptotically late times, with μ being field mass. Our result seems to suggest that the intermediate tails t-(l+3/2)sin(μt) and the asymptotically tails t-5/6sin(μt) may be a quite general feature for evolution of massive scalar fields in any four-dimensional asymptotically flat rotating black hole backgrounds.
 Select Squeezing and Entanglement in Continuous Variable Systems XIA Yun-Jie, GUO Guang-Can Chin. Phys. Lett. 2004, 21 (10): 1877-1880 .   Abstract   PDF(pc) (207KB) ( 604 ) Based on total variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators, the generalized EPR entangled states in continuous variable systems are defined. We show that such entangled states must correspond to two-mode squeezing states whether these states are Gaussian or not and whether they are pure or not. With help of the relation between the total variance and the entanglement, the degree of such entanglement is also defined. Through analysing some specific cases, we see that this method is very convenient and easy in practical applications. In addition, an entangled state with no squeezing is studied, which reveals that there certainly exists something unknown about entanglement in continuous variable systems.
 Select Stability of Bright Solitons in Bose--Einstein Condensates YU Hui-You, YAN Jia-Ren, XIE Qiong-Tao Chin. Phys. Lett. 2004, 21 (10): 1881-1883 .   Abstract   PDF(pc) (234KB) ( 544 ) We investigate the stability of bright solitons in Bose-Einstein condensates by including a feeding term and a loss one in the Gross-Pitaevskii equation. Based on the direct approach of perturbation theory for the nonlinear Schrödinger equation, we give the explicit dependence of the height and other related quantities of bright solitons on the feeding and loss term. It is found that the three-body recombination loss plays a crucial role in stabilizing bright solitons.
 Select Dynamical Equation of Post Newtonian Quasi-rigid Body XU Chong-Ming, TAO Jin-He, HUANG Tian-Yi, WU Xue-Jun Chin. Phys. Lett. 2004, 21 (10): 1884-1886 .   Abstract   PDF(pc) (210KB) ( 417 ) We derive the dynamical equation of a post Newtonian (PN) quasi-rigid body from the general rotational equation of motion, i.e. the PN rotational equation of motion for a quasi-rigid body. It is emphasized that a rotational angular velocity vector and a figure axis besides the first post Newtonian (1PN) spin vector can be defined and realized for the model of a PN quasi-rigid body model constructed recently. Actually, we have shown that the moment of inertia tensor of a quasi-rigid body can be transformed into a diagonal form by an orthogonal transformation, which defines the principal axes of inertia of the body. As an example, its torque-free motion is discussed and a PN Poinsot configuration, which is similar to the Newtonian one with a small 1PN correction, is solved.
 Select Sommerfeld’s Quantum Condition of Action and the Spectra of Quantum Schwarzschild Black Hole LIU Liao, PEI Shou-Yong Chin. Phys. Lett. 2004, 21 (10): 1887-1889 .   Abstract   PDF(pc) (191KB) ( 701 ) If the situation of quantum gravity nowadays is nearly the same as that of quantum mechanics in its early time of Bohr and Sommerfeld, then a first-step study of the quantum gravity under Sommerfeld's quantum condition of action might be helpful. We present the spectra of quantum Schwarzschild black hole in non-relativistic quantum mechanics. It is found that the quantum of area is 8π/3l2p, the quantum of entropy is 2π/3kB, and the Hawking evaporation will cease when the black hole reaches the ground state m=
 Select Double Noncommutative Jackiw--Teitelboim Gravity Model in 1+1 Dimensions WU Ya-Bo, SHAO Ying, GUI Yuan-Xing Chin. Phys. Lett. 2004, 21 (10): 1890-1892 .   Abstract   PDF(pc) (212KB) ( 908 ) We establish a double noncommutative Jackiw-Teitelboim (JT) gravity model in 1+1 dimensions, which extends the results of Cacciatori et al. (Class. Quant. Grav. 19(2002)4029) by means of the double complex function theory. Not only can the two cases of the cosmological constant λ>0 and λ<0 be discussed in a unified way, but also the double solutions of this model, i.e. the de Sitter (dS2) and anti-de Sitter (AdS2) fuzzy spheres, can be derived simultaneously. Hence the results of Cacciatori et al. are included as a special case.
 Select Bound State Solutions of the Dirac Equation for the Kratzer Potential Lalit K. Sharma, Joseph Fiase Chin. Phys. Lett. 2004, 21 (10): 1893-1895 .   Abstract   PDF(pc) (183KB) ( 560 ) We present exact solutions of the Dirac equation for two electromagnetic potentials, i.e. the vector and the scalar potentials. These solutions are written in terms of the known solutions of the Schrödinger equation. The presentation is within the two-component relativistic description. Mainly the bound state solutions have been obtained.
 Select Colour Dipole Picture for Deep Inelastic Scattering in the Collinear Factorization Scheme SHEN Zhen-Qi, ZHU Wei Chin. Phys. Lett. 2004, 21 (10): 1896-1899 .   Abstract   PDF(pc) (430KB) ( 461 ) The colour dipole picture for deep inelastic scattering processes is generalized in the collinear factorization scheme. We show that a duality between the colour dipole picture and scattering picture is lost in higher twist amplitudes.
 Select Strangeness Production in Ultrarelativistic Nucleus-Nucleus Collisions LONG Jia-Li, HE Ze-Jun, , MA Yu-Gang, , MA Guo-Liang, Chin. Phys. Lett. 2004, 21 (10): 1900-1903 .   Abstract   PDF(pc) (317KB) ( 415 ) Based on the relaxation equations describing the chemical quilibration of gluons, quarks and s quarks at finite baryon ensity derived from the Jüttner distribution of partons, with the help of a rapid phase transition scenario from quark hase to hadron phase, we calculate strangeness production in the quark phase and hadron phase. It is found that the K-/π- ratio is enhanced to be larger than that in pp collisions by about a factor 3.
 Select High-Spin Structure in Neutron-Rich 108Ru Nucleus CHE Xing-Lai, ZHU Sheng-Jiang, J. H. Hamilton, A. V. Ramayya, J. K. Hwang, U Yong-Nam, LI Ming-Liang, ZHENG Rang-Chen, I. Y. Lee, J. O. Rasmussen, Y. X. Luo, W.C.Ma Chin. Phys. Lett. 2004, 21 (10): 1904-1907 .   Abstract   PDF(pc) (843KB) ( 857 ) High spin states in the neutron-rich 108Ru nucleus have been studied through measuring prompt γ-ray coincidences following the spontaneous fission of 252Cf with the Gammasphere detector array. The yrast band has been confirmed. The one-phonon γ-vibrational band and the two-quasiparticle band based on the 5- level have been extended up to 13+ and 15-, respectively. In addition, two levels at 1644.8keV and 1826.5keV excitation energies are newly identified and proposed to be the members of a two phonon γ-vibrational band. It is shown that the 108Ru nucleus has triaxial deformation with parameters β2～0.29 and γ=-22°from the total Routhian surface calculations. The observed band crossing in the yrast band is due to the alignment of a pair of h11/2 neutrons according to the cranked shell model calculations. The possible configuration for the two-quasiparticle band has been discussed.
 Select Highly Sensitive Tunable Diode Laser Absorption Spectroscopy of CO2 Around 1.31μm SHAO Jie, GAO Xiao-Ming, DENG Lun-Hua, HUANG Wei, YANG Yong, PEI Shi-Xin, YUAN Yi-Qian, ZHANG Wei-Jun Chin. Phys. Lett. 2004, 21 (10): 1908-1910 .   Abstract   PDF(pc) (477KB) ( 461 ) Fifteen new absorption lines are observed when studying CO2 absorption spectroscopy by wavelength modulation (WM) technique with a distributed feedback laser. The overtone spectra of CO2 around 1.31μm and the corresponding spectral parameters (i.e. positions, intensities, self-broadening coefficients) are presented. The intensity of the weakest line detected is 2.25163×10-27cm-1/(molecule.cm-2 at the pressure of 5Torr, with a corresponding absorption of 3.88×10-8
 Select Angular Distribution and Angular Dispersion in Collision of 19F+27Al at 114MeV WANG Qi, DONG Yu-Chuan, LI Song-Lin, DUAN Li-Min, XU Hu-Shan, XU Hua-Gen, CHEN Ruo-Fu, WU He-Yu, HAN Jian-Long, LI Zhi-Chang, LU Xiu-Qin, ZHAO Kui, LIU Jian-Cheng, SERGEY Yu-Kun, Chin. Phys. Lett. 2004, 21 (10): 1911-1913 .   Abstract   PDF(pc) (467KB) ( 394 ) Angular distributions of fragments B, C, N, O, F, Ne, Na, Mg and Al induced by the collision of 19F+27Al at 114MeV have been measured. Angular dispersion parameters are extracted from the experimental data and compared with the theoretical ones. The dynamic dispersions for dissipative products depend strongly on the charge number Z of the fragments.
 Select Isospin Effect of Coulomb Interaction on Momentum Dissipation in Intermediate Energy Heavy Ion Collisions LIU Jian-Ye, , GUO Wen-Jun, XING Yong-Zhong, LI Xi-Guo, Chin. Phys. Lett. 2004, 21 (10): 1914-1917 .   Abstract   PDF(pc) (396KB) ( 352 ) We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon--nucleon cross section. In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon--nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon--nucleon cross section and weakly on the symmetry potential.
 Select Pion Interferometry for Hydrodynamical Expanding Source with a Finite Baryon Density ZHANG Wei-Ning, EFAAF M. J, WONG Cheuk-Yin, KHALILIASR M Chin. Phys. Lett. 2004, 21 (10): 1918-1921 .   Abstract   PDF(pc) (331KB) ( 476 ) We calculate the two-pion correlation function for an expanding hadron source with a finite baryon density. The space--time evolution of the source is described by relativistic hydrodynamics and the Hanbury-Brown-Twiss (HBT) radius is extracted after effects of collective expansion and multiple scattering on the HBT interferometry have been taken into account, using quantum probability amplitudes in a path-integral formalism. We find that this radius is substantially smaller than the HBT radius extracted from the freeze-out configuration.
 Select Accuracy Measurements of the CAS-LIBB Single-Particle Microbeam for Single Cell Irradiation WANG Xu-Fei, HU Zhi-Wen, WANG Xiao-Hua, CHEN Lian-Yun, ZHANG Jun, LI Jun, CHEN Bin, XU Ming-Liang, WU Yu, WU Li-Jun, YU Zeng-Liang Chin. Phys. Lett. 2004, 21 (10): 1922-1925 .   Abstract   PDF(pc) (374KB) ( 454 ) A single-particle microbeam facility has been constructed at the Laboratory of Ion Beam Bioengineering (LIBB), Chinese Academy of Sciences. The system is designed to deliver the defined number of hydrogen ions, covering a range of energy from 1.0 to 3.5MeV, into an area smaller than the nuclei of individual living cells. Accuracy of the particle detection system and the cell targeting system in the facility has been assessed using CR39 (nuclear track detector) for 2.3MeV protons. The results demonstrate that the particle detection efficiency is above 98%, and the overall targeting accuracy of the microbeam is limited within 3μm for more than 90% hits.
 Select Analytic Solutions of Three-Level Dressed-Atom Model WANG Zheng-Ling, YIN Jian-Ping Chin. Phys. Lett. 2004, 21 (10): 1926-1929 .   Abstract   PDF(pc) (358KB) ( 910 ) On the basis of the dressed-atom model, the general analytic expressions for the eigenenergies, eigenstates and their optical potentials of the Λ-configuration three-level atom system are derived and analysed. From the calculation of dipole matrix element of different dressed states, we obtain the spontaneous-emission rates in the dressed-atom picture. We find that our general expressions of optical potentials for the three-level dressed atom can be reduced to the same as ones in previous references under the approximation of a small saturation parameter. We also analyse the dependences of the optical potentials of a three-level 85Rb atom on the laser detuning and the dependences of spontaneous-emission rates on the radial position in the dark hollow beam, and discuss the probability (population) evolutions of dressed-atomic eigenstates in three levels in the hollow beam.
 Select Optimal Control of Population Transfer in Three-Level Λ System with Genetic Algorithms ZHANG Xiang-Yun, SUN Zhen-Rong, CHEN Guo-Liang, WANG Zu-Geng, Xü Zhi-Zhan, LI Ru-Xin Chin. Phys. Lett. 2004, 21 (10): 1930-1933 .   Abstract   PDF(pc) (565KB) ( 445 ) Population transfer in a three-level Λ system is simulated numerically and optimized. Almost complete population transfer from |1> to |3> is achieved by a genetic algorithm while the population in state |2> reached minimum over the entire evolution at the same time. The result shows that the optimal pulse sequence is the well-known stimulated Raman adiabatic passage (STIRAP) scheme. The detuning of pump pulse and Stokes pulse Δp and Δs with the opposite sign and the chirps xp and xs with the same sign are in favour of the complete and robust population transfer for few-cycle laser pulse. Rabi frequencies Ωp and Ωs have insensitive effects on the complete population transfer during a large scope of their ratio when they are large enough.
 Select Reverse Energy-Pooling Collisions: Cs(9D)+Na(3S)→ Cs(6P)+Na(3P) SHEN Yi-Fan, Pulati A, DAI Kang Chin. Phys. Lett. 2004, 21 (10): 1934-1936 .   Abstract   PDF(pc) (238KB) ( 335 ) We report the observation of a heteronuclear reverse energy pooling process Cs(9D)+Na(3S)→Cs(6P)+Na(3P). The state is populated in a stepwise excitation process by a dye-laser beam. A double-modulation technique is used to select the fluorescence contribution at the Na(3PJ) exit channels only due to the above reaction. The ground-state sodium atom density was obtained by measuring the wing absorption coefficient. The measured density and fluorescence intensities are used to obtain the reverse energy-pooling rate coefficient. The cross section related to the rate coefficient is (4.3±1.4)×10-14cm2.
 Select Dielectronic Recombination of Ni-Like Gold Ion Through the Cu-Like 3d94ln’l’(n’= 4,5) Configurations SHI Xi-Heng, CHEN Chong-Yang, WANG Yan-Sen, GU Ming-Feng Chin. Phys. Lett. 2004, 21 (10): 1937-1940 .   Abstract   PDF(pc) (447KB) ( 408 ) Ab initio calculations of dielectronic recombination (DR) rate coefficients from the ground state of Ni-like Au ion through the Cu-like 3d94ln’l’(n’= 4,5) configurations have been performed by using a relativistic atomic code FAC with configuration interaction. The DR rate coefficients through the 3d94l5f5/2 and 3d94l5f7/2 configurations are evaluated separately. The contributions from resonant and nonresonant radiative stabilizing transitions to the total rate coefficients are distinguished and discussed. The decays to autoionizing levels followed by radiative cascades are included in the calculation.
 Select Synthesis of Bio-organic Molecules of Life Induced by Low Energy Ion Implantation WANG Xiang-Qin, HAN Jian-Wei, WANG Wei, YU Zeng-Liang Chin. Phys. Lett. 2004, 21 (10): 1941-1943 .   Abstract   PDF(pc) (351KB) ( 419 ) Gase discharge and ion implantation are respectively used in some simple water solution and solid molecular samples. The implanted samples are analysed by the 1H nuclear magnetic resonance spectra and the Fourier transform infrared spectroscopy. The results show that some new NO-2 anion, NO-3 anion, dimethyl ether, and ethanol are formed in the water solution samples with nitrogen, methane and carbon dioxide gas discharge. New cyano groups (-CN) and amino groups (-NH2) are formed in the irradiated solid sodium carboxylic sample with N+ ion irradiation. The experimental results present a new way to synthesize small molecules of life by low-energy ion implantation.
 Select Influence of Optical Feedback from Birefringence External Cavity on Intensity Tuning and Polarization of Laser FEI Li-Gang, ZHANG Shu-Lian, WAN Xin-Jun Chin. Phys. Lett. 2004, 21 (10): 1944-1947 .   Abstract   PDF(pc) (491KB) ( 794 ) The characteristics of intensity tuning and polarization of He-Ne laser with optical feedback are studied. When the internal cavity length of the laser with birefringence optical feedback is tuned, not only does output intensity vary with laser frequency, but also the polarization periodically hops between two orthogonal directions. If the phase difference of birefringence is π/2, two polarization states alternately oscillate and have equal bandwidths within the longitudinal mode spacing. The times of polarization flipping in the longitudinal mode bandwidth is proportional to the ratio of external cavity length to internal cavity length. The experimental results are explained, and the potential uses are also discussed.
 Select Lasering in a Waveguide with Scatterers in Diameter 20nm LIU Chun-Xu, LIU Jun-Ye, ZHANG Jia-Hua, DOU Kai Chin. Phys. Lett. 2004, 21 (10): 1948-1950 .   Abstract   PDF(pc) (464KB) ( 429 ) We report random lasing achieved in a MEH-PPV/glass waveguide with the TiO2 scatterers in diameter 20nm that is significantly smaller than submicrometre of TiO2 scatterers in the films or suspensions previously reported on random lasing. The spectral lines are dramatically narrowed by almost two orders of magnitude compared with those excited by a xenon lamp. The amplified spontaneous emission is identified as the dominant mechanism in our system. Light localization might be achieved in a broad class of random materials based on the features of the mean free path l*=5.4×105nm, kl*>>1 and the Thouless number 6.73×10-5 with k being the wave number.
 Select High-Power Red Light Generation by Intra-Cavity Frequency-Doubling of a Side-Pumped Nd:YAG Laser in a LiB3O5 Crystal SUN Zhi-Pei, LI Rui-Ning, BI Yong, YANG Xiao-Dong, BO Yong, HOU Wei, ZHANG Ying, WANG Gui-Ling, ZHAO Wu-Li, ZHANG Hong-Bo, CUI Da-Fu, XU Zu-Yan Chin. Phys. Lett. 2004, 21 (10): 1951-1953 .   Abstract   PDF(pc) (339KB) ( 498 ) We report the generation of high-power red light radiation of 11.2W in a LiB3O5(LBO) crystal with intra-cavity frequency doubling of two compact and simple side-pumped Nd:YAG laser modules under a repetition rate of 3.5kHz. The pulse width of output is about 180±20,ns. The beam quality of the M2 value is 15±3 in both the directions. This excellent laser performance demonstrates that the Nd:YAG laser with LBO intracavity frequency doubling is an promising method for generating red light with high brightness.
 Select Gain Clamped Two-Stage Double-Pass L-Band EDFA with a Single Fibre Bragg Grating Sulaiman Wadi Harun, Harith Ahmad Chin. Phys. Lett. 2004, 21 (10): 1954-1957 .   Abstract   PDF(pc) (443KB) ( 691 ) A gain clamping is demonstrated in a two-stage double-pass L-band erbium-doped fibre amplifier (EDFA) by using a single fibre Bragg grating. Two types of the fibre-Bragg-grating (FBG) broadband and narrowband have been used in the gain-clamped system. The combination of the FBG and the optical circulator has created a laser in the cavity for gain clamping. The application of a broadband FBG has improved the amplifier’s efficiency and noise figure compared to the narrowband FBG system. The gain is clamped at about 22.1dB for the amplifier with broadband FBG with gain variation of less than ±0.15dB and the input saturation power Psat at -8dBm. The gain varies from 19.0 to 25.4dB in the signal wavelength region of 1574nm-1604nm. The noise figure varies from 6.0 to 10.8dB at this wavelength range. The noise figure values are found to improve by as much as 0.3-1.1dB when compared to the unclamped amplifier for signal wavelengths above 1580nm. The high clamped gain and low noise figure are obtained due to the suppression of the backward C-band amplified spontaneous emission. The gain clamped amplifier shows only a small power excursions when three of the four channels are added/dropped. The effects of relaxation oscillation are not seen for the gain-clamped two-stage double-pass L-band EDFA.
 Select High Two-Beam Coupling Coefficients of Monolithic Small Molecule at Low Electric Field ZHANG Jie, CHEN Zhi-Jian, HUANG Mao-Mao, LI Fu-Shan, WEI Qun, LIU Yi-Hong, GONG Qi-Huang Chin. Phys. Lett. 2004, 21 (10): 1958-1960 .   Abstract   PDF(pc) (411KB) ( 516 ) A novel full-functional photorefractive small molecular material,(9-ethyl-9H-carbazol-3-ylmethylene)-(4-nitro-phenyl)-amine (ECYENPA), was synthesized and its photorefractivity was studied by two-beam coupling experiments at a wavelength of 632.8nm. The glass transition temperature of ECYENPA, as low as -5°C, results in the chromophore being orientated easily at room temperature. High two-beam coupling coefficient was obtained to be 232cm-1 at an electric field of 44.6V/μm.
 Select A Random Number Generator Based on Quantum Entangled Photon Pairs MA Hai-Qiang, WANG Su-Mei, ZHANG Da, CHANG Jun-Tao, JI Ling-Ling, HOU Yan-Xue, WU Ling-An Chin. Phys. Lett. 2004, 21 (10): 1961-1964 .   Abstract   PDF(pc) (290KB) ( 974 ) A new scheme for a random number generator based on quantum entangled photon pairs is demonstrated. Signal photons produced by optical parametric down-conversion are detected at two single-photon detectors after transmission or reflection at a 50/50% beamsplitter, to form a truly random binary sequence. Their arrival is signalled by their twin idler photons, so that a cw laser source may be used instead of attenuated laser pulses. Coincidence measurement is employed to obtain the bit sequences, which are shown to fully satisfy the standard tests for randomness.
 Select Widely Tunable Femtosecond Soliton Pulse Generation by Using Soliton-Frequency Shift in a Photonic Crystal Fibre CHENG Chun-Fu, WANG Xiao-Fang, SHEN Bai-Fei Chin. Phys. Lett. 2004, 21 (10): 1965-1968 .   Abstract   PDF(pc) (446KB) ( 557 ) Femtosecond Raman soliton generation, tunable from 800 to 1044nm, has been theoretically investigated for a photonic crystal fibre pumped by a 200-fs pulse. A highly nonlinear photonic crystal fibre with a length of only 57.7cm and a nonlinear coefficient of 0.075(Wm)-1 is used to achieved such a broadband. It is found that the spectral bandwidth increases with the input peak power. In particular, it is also found that the output wavelengths of the resulting sub-40fs Raman solitons can also be tuned effectively by varying the initial pulse chirp. There exists an optimal positive chirp which maximizes the bandwidth, corresponding to the formation of only one long-wavelength Raman soliton.
 Select All-Optical Photorefractive Effect in Bihole-Transporting System Polymeric Composites HUANG Mao-Mao, CHEN Zhi-Jian, ZHANG Jie, WEI Qun, LIU Yi-Hong, GONG Qi-Huang, BAI Yao-Wen, CHEN Xiao-Fang, WAN Xin-Hua, ZHOU Qi-Feng Chin. Phys. Lett. 2004, 21 (10): 1969-1972 .   Abstract   PDF(pc) (489KB) ( 547 ) Photorefractive (PR) composites based on poly(N-vinylcarbozale) and azobenzene have been fabricated. Two-beam-coupling and four-wave-mixing phenomena were observed in the absence of an external electric field or prepoling. The maximum two-beam-coupling gain coefficient and the refractive index modulation were measured to be 79cm-1 and 2.2×10-4 respectively. The all-optical-PR phenomenon is explained based on the photoassisted poling of the azo dye by the synergism of the photoisomerization and the longitudinal electric field due to longitudinal intensity gradient of writing light beams. The bi-hole-transporting system provides more charge-carrier traps resulting in improvement of PR performance.
 Select High-Density Read-Only Memory Disc with Ag11In12Sb51Te26 Super-Resolution Mask Layer ZHANG Feng, WANG Yang, XU Wen-Dong, SHI Hong-Ren, WEI Jing-Song, GAN Fu-Xi Chin. Phys. Lett. 2004, 21 (10): 1973-1975 .   Abstract   PDF(pc) (389KB) ( 500 ) A novel read-only memory (ROM) disc with an Ag11In12Sb51Te26 super-resolution mask layer is proposed and investigated for the first time to our knowledge. The carrier-to-noise ratio of more than 40dB could be obtained from small pits (380nm), which are below the readout resolution limit (400nm), in our dynamic setup with a wavelength of 632.8nm and numerical aperture of 0.40. Dependences of carrier-to-noise ratio on readout power, readout velocity and film thickness are studied. The results show that the optimum film thickness is 20-50nm and the corresponding carrier-to-noise ratio is more than 40dB at readout power of 4mW and readout velocity of 2m/s in our experiment. The super-resolution readout mechanism for this ROM disc is also discussed.
 Select Ultrasonic Scattering by an Elastic Sphere in Matrix with Imperfect Interface WU Rui-Xin, WANG Yao-Jun, Chin. Phys. Lett. 2004, 21 (10): 1976-1978 .   Abstract   PDF(pc) (308KB) ( 459 ) The general solution of ultrasonic wave scattering by an elastic sphere embedded in solid matrix with an interface layer is developed. A transfer matrix connecting the displacement and stress components on the opposite surfaces of the layer is derived. Asymptotically expanding the transfer matrix gives the equivalent boundary conditions at an interface. A spring model for describing physically a spherical imperfect interface is thus established and its validity is evaluated. Ultrasonic scatterings respectively from rigid and slip interface are numerically compared.
 Select Localized Mode Enhanced Coupler Based on Quasi-One-Dimensional Photonic Crystal Microstrip LI Yun-Hui, JIANG Hai-Tao, HE Li, LI Hong-Qiang, ZHANG Ye-Wen, CHEN Hong Chin. Phys. Lett. 2004, 21 (10): 1976-1978 .   Abstract   PDF(pc) (286KB) ( 511 ) We propose a novel localized mode enhanced (LME) coupler based on quasi-one-dimensional photonic crystal microstrips, which is promising to be applied in wavelength division multiplexed microwave communication systems. Compared to the traditional microstrip coupler, the LME structure has two advantages: high efficiency and frequency selectivity. Even in a relatively far coupling distance, this structure can still achieve a high efficiency about 50%. The frequency selectivity can be realized by simply tuning the distance between two transmission lines.
 Select An Approximately Analytical Solution for the Marangoni Convection in an In-Ga-Sb System ZHENG Lian-Cun, CHEN Xue-Hui, ZHANG Xin-Xin, HE Ji-Cheng Chin. Phys. Lett. 2004, 21 (10): 1983-1985 .   Abstract   PDF(pc) (259KB) ( 668 ) We present a similarity analysis for the Marangoni convection in a rectangular open boat. Furthermore, an efficient analytical decomposition and a numerical technique are provided. The approximately analytical solution may be represented in terms of a rapid convergent power series with elegantly computable terms. The results are compared with the numerical ones in the literature and the associated transfer behaviour is analysed.
 Select Thermalcapillary Convection in NaBi(WO4)2 Melt HONG Yong, JIN Wei-Qing, PAN Xiu-Hong Chin. Phys. Lett. 2004, 21 (10): 1986-1988 .   Abstract   PDF(pc) (360KB) ( 496 ) Surface-tension driven flow in NaBi(WO4)2 melt is visualized by means of the already proved method of high temperature in situ optical observation. The transition phenomena of the melt from steady spatial to oscillatory behaviour in melt are observed. The oscillatory thermocapillary convection is accompanied by synchronous temperature oscillations with the frequency 10Hz. The onset temperature of thermocapillary convection varies with the change of meniscus curvature of the melt free surface, which probably due to the liquid pressure at the surface associated with the curvature of meniscus. The oscillatory frequency is proportional to the temperature. Finally, another kind of oscillatory thermocapillary convection with the frequency about 5Hz dominating in the undercooled melt is also observed.
 Select Three Kinds of Velocity Structure Function in Turbulent Flows LIU Wei, JIANG Nan Chin. Phys. Lett. 2004, 21 (10): 1989-1992 .   Abstract   PDF(pc) (498KB) ( 824 ) Based on the local multi-scale eddy structures in turbulent flows, we elucidate the essential difference between the real turbulent field with a finite Reynolds number and the Kolmogorov fully developed random field. The motion of fluid particles in the real turbulent field is not fully random. There exist multi-scale structures due to the effect of viscosity. Actually the movements of fluid particles in the turbulent field are restricted by such eddy structures. Furthermore, concept of the locally averaged velocity structure function is put forward to describe the relative strain distortion of two adjacent turbulent eddy structures at a certain scale. The time sequence of the longitudinal velocity component at different vertical locations in turbulent boundary layer has been elaborately measured by the constant temperature anemometry of model IFA-300 in a wind tunnel. The experiment proves that the locally averaged velocity structure function is in agreement with the wavelet-coefficient structure function.
 Select Analysis of Instabilities in Non-Equilibrium Plasmas IN Lie, WU Bin, ZHANG Peng, WANG Yong-Qing Chin. Phys. Lett. 2004, 21 (10): 1993-1996 .   Abstract   PDF(pc) (352KB) ( 418 ) Plasma instabilities with charged particle production processes in non-equilibrium plasma are analysed. A criterion on plasma instabilities is deduced by first-order perturbation theory. The relationship between plasma instabilities and certain factors (degree of non-equilibrium in plasma, the electron attachment rate coefficient and electron temperature) are described.
 Select Effect of Electron Drift Velocity on Whistler Instability in Collisionless Magnetic Reconnection WANG De-Yu, HUANG Guang-Li, LU Quan-Ming Chin. Phys. Lett. 2004, 21 (10): 1997-2000 .   Abstract   PDF(pc) (342KB) ( 441 ) The whistler instability is studied under the condition that the electron and ion velocities can be described in a bi-Maxwellian distribution with a field-aligned electron outflow drift velocity. It is found that the electron outflow drift velocity might obviously make the threshold condition of whistler instability decrease when this velocity is parallel to the magnetic field, whereas the electron outflow drift velocity might increase the threshold condition when this velocity is anti-parallel to the magnetic field in collisionless magnetic reconnection.
 Select Effect of Magnetic Field and Equilibrium Flow on Rayleigh-Taylor Instability WU Zheng-Wei, ZHANG Wen-Lu, LI Ding, YANG Wei-Hong Chin. Phys. Lett. 2004, 21 (10): 2001-2004 .   Abstract   PDF(pc) (335KB) ( 581 ) We investigate the effect of a finite equilibrium flow and magnetic field on the Rayleigh-Taylor instability. It is found that the equilibrium flow only makes a frequency shift of perturbation and the growth rate of the Rayleigh-Taylor instability remains unchanged. However, the magnetic field can change the growth rate and, in particular, a very strong magnetic field suppresses the growth rate.
 Select Theoretical Calculations of Opacity for Non-Local-Thermodynamic-Equilibrium Plasmas PANG Jin-Qiao, WU Ze-Qing, YAN Jun, HAN Guo-Xing Chin. Phys. Lett. 2004, 21 (10): 2005-2007 .   Abstract   PDF(pc) (338KB) ( 640 ) A method is presented to calculate the spectral-resolved opacity for non-local-thermodynamic-equilibrium plasmas. With the present method, the configuration population is obtained by solving the rate equations within the framework of configuration-averaged approximation in which the cross sections are calculated based on the first-order perturbation theory. The transition properties are calculated by using the unresolved transition array model. As the illustration, the frequency-dependent opacities of Al and Au plasmas are calculated and compared with the simulation results of the super configuration collisional radiative code. General agreements are obtained and there are some discrepancies for opacity of high-Z elements.
 Select Structures and Properties of Zr--N Films Prepared by ECR-Microwave Plasma Source Enhanced Direct-Current Magnetron Sputtering Under Different N2 Partial Pressures LIU Tian-Wei, DENG Xin-Lu, WAN Xiao-Ying, WANG Ying-Min, ZOU Jian-Xin, DONG Chuang Chin. Phys. Lett. 2004, 21 (10): 2008-2011 .   Abstract   PDF(pc) (448KB) ( 629 ) ZrN thin films were prepared on 45# steel by using ECR-microwave plasma source enhanced dc magnetron sputtering. The increase of the N2 partial pressure PN2 leads to phase transitions from ZrN and an orthorhombic ZrNx phase to an amorphous phase. At PN2=1.1×10-2Pa to 4.5×10-2Pa, the films contain both ZrN and ZrNx (a=0.3585, b=0.4443, c=0.5798nm). At PN2=5.0×10-2Pa, the film shows a strong tendency towards the amorphous phase. The N concentration at different PN2 varies from 7.73 to 66.96% according to electron probe analysis. The microhardness of the samples, varying from 19.82GPa to 26.73GPa, first increases and then decreases with increasing PN2. The hardest sample has a wear rate of about 4.5×10-5mg/min. The property changes are relative to the film structure due to different N2 partial pressures.
 Select Isomer Spectrum of Small Carbon Clusters SHENG Yang, LI Peng, NING Xi-Jing Chin. Phys. Lett. 2004, 21 (10): 2012-2015 .   Abstract   PDF(pc) (563KB) ( 454 ) A theoretical method is developed to find isomers of cluster particles,and the isomer spectrum of carbon clusters Cn(n=3-44) is obtained. It is found that the isomers of 3-11 atoms are in either mono-ring or line shapes, while the isomers of 12-18 atoms show flat sheet shapes. As cluster size increases, bowl isomers become more (n>19) until cage isomers dominate the structures (n>27). Based on the isomer spectrum, results of a previous experiment are interpreted.
 Select Improvement of Properties of p-GaN by Mg Delta Doping PAN Yao-Bo, YANG Zhi-Jian, LU Yu, LU Min, HU Cheng-Yu, YU Tong-Jun, HU Xiao-Dong, ZHANG Guo-Yi Chin. Phys. Lett. 2004, 21 (10): 2016-2018 .   Abstract   PDF(pc) (286KB) ( 965 ) The Mg-delta-doped GaN structure has been grown by low-pressure metalorganic chemical vapour deposition. The Hall-effect measurements reveal that the electrical properties are enhanced. The hole concentration is enhanced twice and hole mobility is enhanced three times by Mg-delta doping. Both the etch pit density data and the x-ray diffraction data demonstrate that Mg-delta doping can reduce the threading dislocation density of p-type GaN epilayer.
 Select Shock Melting Temperature of Initially Porous Iron and Indication for Melting Curve of Iron at High Pressures LI Xi-Jun, ZHANG Dai-Yu, LIU Fu-Sheng, JING Fu-Qian Chin. Phys. Lett. 2004, 21 (10): 2019-2021 .   Abstract   PDF(pc) (328KB) ( 474 ) The melting curve of iron is crucial for modelling of the earth’s internal heat structures and to understand melting of solids at high pressures. However, the measured melting temperatures of iron at high pressures are disparate so far. We measured the shocked interface (porous iron/sapphire window) temperatures of a kind of porous iron. By using a model for shock temperature measurement [High Pressures Res. 2 (1990) 159] and the previous results of sound velocity measurements [Chin. Phys. Lett. 18 (2001) 852], we determine the melting temperatures of iron at shock compression high pressures of 145 and 171GPa. They are consistent with the results reported by other shock compression experiments. Based on the possible different melting mechanisms of iron in diamond anvil cell and in shock compression, the corrected melting temperatures of iron at high pressures become more consistent.
 Select Deoxygenation Enhanced Double-Resistivity-Peak Properties in Polycrystalline La0.7Ca0.3Mn0.92Cr0.08O3-δ FANG Jun, TIAN Jian-Jun, WANG Fang, SONG Wen-Hai, HUANG Zhen, CHEN Jing-Lin Chin. Phys. Lett. 2004, 21 (10): 2022-2025 .   Abstract   PDF(pc) (494KB) ( 376 ) Influences of deoxygenation on the resistivity and the magnetic properties of La0.7Ca0.3Mn0.92Cr0.08O3-δ(M = Al, Cr) are compared to understand the peculiar doping effect of chromium in the ferromagnetic manganites. It is found that the double resistivity bumps exhibited by the Cr-doped compounds can be tuned by the oxygen content. We have related the double-bump feature with the well-known inefficiency of Cr in lowering TC, and interpreted both the features consistently in terms of large-scale phase separation. It is suggested that the large-scale phase separation is a general characteristic of Cr-doped manganites, and many unusual phenomena exhibited by Cr doping are directly related to the large-scale phase separation.
 Select Measurement of Surface Potential at Metal/Organic-Material Interfaces by Electro-Absorption Method CHENG Xiao-Man, YAO Su-Wei, LI Cheng-Quan, MANAKA Takaaki, IWAMOTO Mitsumasa Chin. Phys. Lett. 2004, 21 (10): 2026-2028 .   Abstract   PDF(pc) (425KB) ( 446 ) The surface potential built-in vacuum deposited phthalocyanine (Pc) film on aluminium electrode is investigated by the electro-modulation method. To avoid the influence of charge injection, a sandwiched cell (Al-Pc-air-ITO) is fabricated. The modulation signal, which depends on the external electric field intensity, is detected. The properties of electro-absorption (EA) and electro-reflectance (ER) signals are analysed. The existence of the surface potential at the metal/organic-material interface induces 1f referenced ER signals. As a result, the surface potential built across the vacuum-deposited Pc film on the aluminium electrode is estimated to be 1.23V.
 Select Nucleation Behaviour in the Initial Stage of Surfactant-Mediated Epitaxial Growth WANG Dai-Mu, SUN Xia, DING Ze-Jun, WU Zi-Qin Chin. Phys. Lett. 2004, 21 (10): 2029-2032 .   Abstract   PDF(pc) (408KB) ( 413 ) The nucleation kinetics in the early stage of epitaxial growth mediated by a monolayer of surfactant is studied by using kinetic Monte Carlo simulations. Our simulation model includes three main kinetic parameters: a small barrier for adatom diffusion on the surfactant terrace, a higher barrier for the exchange of adatoms with their underneath surfactant atoms, and a highest barrier for the recovery exchange in which an exchanged adatom resurfaces to the top of the surfactant layer. The simulations reveal a distinct transition of nucleation behaviour as the different atomic processes are activated successively with increasing temperature. The total nucleus density as a function of temperature exhibits a complex N-shape with a minimum and a maximum, which define the transition temperatures. The characteristic behaviour of nucleation density is helpful to rationalize the experimental observations on the temperature dependence of growth mode in some surfactant-mediated epitaxial systems.
 Select Effect of Coulomb Interaction on Dynamical Localization in a Two-Electron Quantum-Dot Molecule WANG Li-Min, DUAN Su-Qing, ZHAO Xian-Geng, LIU Cheng-Shi Chin. Phys. Lett. 2004, 21 (10): 2033-2036 .   Abstract   PDF(pc) (387KB) ( 329 ) The combined interaction of Coulomb interaction and ac fields with two electrons in a quantum dot molecule is studied respectively with numerical simulation, perturbation theory and the approximation of driven two-level model. The dynamical localization occurs with the ac field whose ratio of the amplitude to the angular frequency is a root of n-order Bessel functions, where n is determined by the Coulomb interaction energy. Such results are explained with either the driven two-level approximation or the degenerated three-level model and verified by the numerical simulations.
 Select Effect of Next-Nearest-Neighbour Hopping on Direct-Current Conductivity Based on an Extended Planar t-J Model DONG Zhan-Hai Chin. Phys. Lett. 2004, 21 (10): 2037-2040 .   Abstract   PDF(pc) (286KB) ( 440 ) By using the self-consistent Born approximation based on a planar extended t- J model, we investigate the relation between dc conductivity and next-nearest-neighbour hopping integral t'. The t'-dependence of dc conductivity shows a peaked structure.
 Select Field Dependence of Magnetization and dM/dH for Sm- and Gd-Doped Bi1.7Pb0.3Sr2Ca2-xRExCu3O10+y Compounds Atilla COSKUN, Ahmet EKICIBIL, Bekir ö, ZCELIK, Kerim KIYMAC Chin. Phys. Lett. 2004, 21 (10): 2041-2044 .   Abstract   PDF(pc) (627KB) ( 848 ) We have performed magnetization measurements as a function of magnetic fields up to 4kOe on Bi1.7Pb0.3Sr2Ca2-xRExCu3O10+y (RE: Gd0.01, Sm0.03, at different fixed temperatures T< Tc in the range 15≤T≤75K. We have observed three important features. Firstly, the dM-dH curves of both the Sm- and Gd-doped samples are similar and each shows a minimum of M at a certain critical field Hc, above which there appears to be a monotonic decrease in magnitude. Secondly, the magnitude of the initial susceptibility dM/dH, related to the superconducting volume, decreases with increasing temperature. In other words, the decrease of dM/dH with T indicates that the superconducting regions reduce in size and the paramagnetic domains probably grow at the expense of superconductivity. The third feature is the fast decrease of hysteresis loops in both the Gd and Sm doped samples with increasing temperature, which implies existence of flux pinning centres. Thus the results show that the Ca2+→ Sm3+ and Gd3+ substitution decreases the hole carrier concentration and hence the volume fraction of the superconducting phase.
 Select Full Aging in Spin Glass State of Y0.90Na0.10MnO3 CHEN Wei-Ran, ZHANG Fu-Chang, MIAO Jun, XU Bo, DONG Xiao-Li, CAO Li-Xin, QIU Xiang-Gang, ZHAO Bai-Ru Chin. Phys. Lett. 2004, 21 (10): 2045-2048 .   Abstract   PDF(pc) (490KB) ( 478 ) We study the decays of the thermoremanent magnetization in Y0.90Na0.10MnO3 for different waiting times at the measuring temperature 33K, well below the spin glass (SG) transition temperature 42K. The results demonstrate that almost perfect full aging can appear even in the case of the cooling time as long as 700s from 60K to 33K. By subtracting the stationary component A(τ0t)a (A is a dimensionless constant, t represents the time, τ0 is the microscopic spin flipping time, and α is a parameter always in the rang of 0.1-0.01), the value of α is found to be much smaller than that reported in other SG systems, which is well consistent with the behaviour of the ac susceptibility. All of them are discussed based on the intrinsic geometric magnetic frustration for the present system.
 Select Strong Electron Field Emission from Nano-CdS Modified Porous Silicon XU Ling, HAN Guan-Qi, WENG Jian, TAM Hoi-Lam, Li King-Fai, ZHANG Yu, XU Jun, HUANG Xin-Fan, CHEAH Kok-Wai Chin. Phys. Lett. 2004, 21 (10): 2049-2050 .   Abstract   PDF(pc) (257KB) ( 700 ) A nano - CdS modified porous silicon (nano - CdS/PS) field emitter is fabricated by chemical method at room temperature. The electron field emission characteristics show that the turn-on field for nano - CdS/PS is about 4.0V/m and the emission current reaches about 20μA/cm2 at 5.0V/μm. This emission current is 20 times larger than that of the PS substrate without nano - CdS modification. The strong field emission properties make the nano - CdS/PS field emitter a good candidate for applications in the field of electronic and optoelectronic devices.
 Select Investigation of Chemical-Vapour-Deposition Diamond Alpha-Particle Detectors GU Bei-Bei, WANG Lin-Jun, ZHANG Ming-Long, XIA Yi-Ben Chin. Phys. Lett. 2004, 21 (10): 2051-2053 .   Abstract   PDF(pc) (408KB) ( 620 ) Diamond films with [100] texture were prepared by a hot-filament chemical vapour deposition technique to fabricate particle detectors. The response of detectors to 5.5MeV241Am particles is studied. The photocurrent increases linearly and then levels off with voltage, and 7nA is obtained at bias voltage of 100V. The time-dependent photocurrent initially increases rapidly and then tends to reach saturation. Furthermore, a little increase of the dark-current after irradiation can be accounted for by the release of the charges captured by the trapping centres at low energy levels during irradiation. An obvious peak of the pulse height distribution can be observed, associated with the energy of 5.5MeV.
 Select Single Cell Element of Chalcogenide Random Access Memory Fabricated with the Focused Ion Beam Method LIU Bo, SONG Zhi-Tang, FENG Song-Lin, CHEN Bomy Chin. Phys. Lett. 2004, 21 (10): 2054-2056 .   Abstract   PDF(pc) (300KB) ( 607 ) A single cell element of chalcogenide random access memory was fabricated by using the focused ion beam method. The contact size between the Ge2Sb2Te5 phase change film and the top electrode film is about 600nm (diameter) and the contact area is calculated to be 0.28μm2. The thickness of the phase change film is 83nm. The current--voltage characteristics of the cell element are studied using the home-made current--voltage tester in our laboratory. The minimum threshold current of about 0.6mA is obtained.
 Select Geometrical Constraint Equations and Geometrically Permissible Condition for Vesicles YIN Ya-Jun, YIN Jie Chin. Phys. Lett. 2004, 21 (10): 2057-2058 .   Abstract   PDF(pc) (188KB) ( 555 ) The application of a geometrical constraint equation for lipid bilayer vesicles is investigated. First, both the physical meaning and the mathematical formulation for the spontaneous curvature of vesicles are clarified. Second, the geometrically permissible conditions and phase diagrams for vesicles, from which the criteria for the formation, existence and disintegration of vesicles may be determined, are revealed.
 Select Investigation of Resistivity of Saturated Porous Media with Lattice Boltzmann Method YUE Wen-Zheng, TAO Guo, ZHU Ke-Qin Chin. Phys. Lett. 2004, 21 (10): 2059-2062 .   Abstract   PDF(pc) (347KB) ( 573 ) The lattice Boltzmann method is employed to study the electrical transport properties of saturated porous media. Electrical current flow through the porous media is simulated and the relationship between resistivity index and water saturation is derived. It is found that this kind of relation is not a straight line as described by the Archie equation with the parameter n being a constant in a log--log scale. A new equation is thus developed to formulate this relation with n being a function of porosity and water saturation. The comparisons between the results by lattice Boltzmann and by the laboratory experiments on rock samples demonstrate that this numerical method can provide an alternative way for the expensive laboratory experiments to investigate the electrical transport properties of saturated porous media and can be used to explore micro mechanisms more conveniently.
 Select Identification of Three Weak Lines and Their Influences on Diagnostics of Electron Temperature and Density in Astrophysical Plasmas LIANG Gui-Yun, ZHAO Gang, SHI Jian-Rong, ZENG Jiao-Long, BIAN Xia Chin. Phys. Lett. 2004, 21 (10): 2063-2066 .   Abstract   PDF(pc) (385KB) ( 507 ) By comparing of the spectra from the Chandra LETGs observation with the synthetic spectra of argon, we identify two weak emission lines, that is, the Ar XV 27.470Å line with transition 2s3p 1P1-2s2 1S0 and the Ar XVI 27.872Å line with transition 3d 2D3/2-2p2P1/2, which blend with the N VII Lyα emission line. Several second-order spectral lines are also identified, one of which is the second-order Fe XVIII 14.534Å line with transition 2p4(3P)3d2F5/2-2p5 2P3/2, which blends with the inter-combination line of He-like N VI. In order to study the effects of these new identified weak lines on the electron temperature and density, we diagnose the two parameters using the intensity ratio of triplets of the He-like N VI and that of resonance lines of H- and He-like N. In the literature, there is a discrepancy of the temperatures deduced from N VI from other He-like ions, such as C V and O VII. The discrepancy disappears after the contribution of these weak lines is taken into account.
 Select Effects of Gyroresonance Absorption and Self Absorption on the Gyrosynchrotron Radiation Spectrum ZHOU Ai-Hua, SU Ying-Na, HUANG Guang-Li Chin. Phys. Lett. 2004, 21 (10): 2067-2070 .   Abstract   PDF(pc) (430KB) ( 578 ) Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum are investigated with a model in a magnetic dipole field. It is found that the gyroresonance absorption and self absorption suppress substantially the gyrosynchrotron radiation at lower frequencies where the radio source is optically thick. The suppression of the gyroresonance absorption on the spectrum increases with the increasing temperature and density of thermal electrons. The suppression of the self absorption on the spectrum increases as increasing number density of the nonthermal electrons. The influences of the gyroresonance absorption and the self one on the spectrum are compared quantitatively. It is shown that only when the number density of the nonthermal electron reaches a higher value of about 3×104cm-3 above 10keV, can the effect of the self absorption on the spectrum compare with the effect of the gyroresonance absorption.
 Select Discovery of Multiple outflows in IRAS 06056+2131 XU Ye, YANG Ji, ZHENG Xing-Wu, SUNADA Kazuyoshi, MA Hong-Jun, SUN Ji-Xian Chin. Phys. Lett. 2004, 21 (10): 2071-2072 .   Abstract   PDF(pc) (217KB) ( 644 ) We report a discovery of multiple outflows in IRAS 06056+2131. The high angular resolution image (～15'') of CO (1--0) emission reveals that the structure of outflow is very complicated. The outflow appears to be everywhere. Its configuration only show a bipolar outflow at observation of both low resolution and low signal-to-noise ratio, while two bipolar outflows can be detected when observed by both high resolution and high signal-to-noise ratio mapping. This result is significant in the understanding of the physical processes that occur at early phase of massive stars.
58 articles
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