technique, generally used in harsh environments, that directly calculates chemical information from a spectrum as analogue output. Neutron spin echo spectroscopy measures internal dynamics in proteins and other soft matter systems. Nuclear quadrupole resonance is a chemical spectroscopy method mediated by NMR of the electric field gradient (EFG) in the absence of magnetic field Perturbed angular correlation (PAC) uses radioactive nuclei as probe to study electric and magnetic fields (hyperfine interactions) in crystals (condensed matter) and bio-molecules. Photoacoustic spectroscopy measures the sound waves produced upon the absorption of radiation. Photoemission spectroscopy Photothermal spectroscopy measures heat evolved upon absorption of radiation. Pump-probe spectroscopy can use ultrafast laser pulses to measure reaction intermediates in the femtosecond timescale. Raman optical activity spectroscopy exploits Raman scattering and optical activity effects to reveal detailed information on chiral centers in molecules. Raman spectroscopy Saturated spectroscopy Scanning tunneling spectroscopy Spectrophotometry Spin noise spectroscopy traces spontaneous fluctuations of electronic and nuclear spins. Time-resolved spectroscopy measures the decay rates of excited states using various spectroscopic methods. Time-stretch spectroscopy Thermal infrared spectroscopy measures thermal radiation emitted from materials and surfaces and is used to determine the type of bonds present in a sample as well as their lattice environment. The techniques are widely used by organic chemists, mineralogists, and planetary scientists. Transient grating spectroscopy measures quasiparticle propagation. It can track changes in metallic materials as they are irradiated. Ultraviolet photoelectron spectroscopy Ultraviolet–visible spectroscopy Vibrational circular dichroism spectroscopy Video spectroscopy X-ray photoelectron spectroscopy Applications There are several applications of spectroscopy in the fields of medicine, physics, chemistry, and astronomy. Taking advantage of the properties of absorbance and with astronomy emission, spectroscopy can be used to identify certain states of nature. The uses of spectroscopy in so many different fields and for so many different applications has caused specialty scientific subfields. Such examples include: Determining the atomic structure of a sample Studying spectral emission lines of the sun and distant galaxies Space exploration Cure monitoring of composites using optical fibers. Estimating weathered wood exposure times using near infrared spectroscopy. Measurement of different compounds in food samples by absorption spectroscopy both in visible and infrared spectrum. Measurement of toxic compounds in blood samples Non-destructive elemental analysis by X-ray fluorescence. Electronic structure research with various spectroscopes. Redshift to determine the speed and velocity of a distant object Determining the metabolic structure of a muscle Monitoring dissolved oxygen content in freshwater and marine ecosystems Altering