Kinetic energy absorption spectroscopy

See also Photoelectron Spectrometers X-Ray Absorption Spectrometers X-Ray Emission Spectroscopy, Applications X-Ray Emission Spectroscopy, Methods X-Ray Fluorescence Spectrometers X-Ray Fluorescence Spectroscopy, Applications Zero Kinetic Energy Photoelectron Spectroscopy, Theory. 

AES Auger electron spectroscopy After the ejection of an electron by absorption of a photon, an atom stays behind as an unstable Ion, which relaxes by filling the hole with an electron from a higher shell. The energy released by this transition Is taken up by another electron, the Auger electron, which leaves the sample with an element-specific kinetic energy. Surface composition, depth profiles... 

X-ray absorption spectroscopy combining x-ray absorption near edge fine structure (XANES) and extended x-ray absorption fine structure (EXAFS) was used to extensively characterize Pt on Cabosll catalysts. XANES Is the result of electron transitions to bound states of the absorbing atom and thereby maps the symmetry - selected empty manifold of electron states. It Is sensitive to the electronic configuration of the absorbing atom. When the photoelectron has sufficient kinetic energy to be ejected from the atom It can be backscattered by neighboring atoms. The quantum Interference of the Initial... 

In addition to measuring total recombination coefficients, experimentalists seek to determine absolute or relative yields of specific recombination products by emission spectroscopy, laser induced fluorescence, and optical absorption. In most such measurements, the products suffer many collisions between their creation and detection and nothing can be deduced about their initial translational energies. Limited, but important, information on the kinetic energies of the nascent products can be obtained by examination of the widths of emitted spectral lines and by... 

In principle, absorption spectroscopy techniques can be used to characterize radicals. The key issues are the sensitivity of the method, the concentrations of radicals that are produced, and the molar absorptivities of the radicals. High-energy electron beams in pulse radiolysis and ultraviolet-visible (UV-vis) light from lasers can produce relatively high radical concentrations in the 1-10 x 10 M range, and UV-vis spectroscopy is possible with sensitive photomultipliers. A compilation of absorption spectra for radicals contains many examples. Infrared (IR) spectroscopy can be used for select cases, such as carbonyl-containing radicals, but it is less useful than UV-vis spectroscopy. Time-resolved absorption spectroscopy is used for direct kinetic smdies. Dynamic ESR spectroscopy also can be employed for kinetic studies, and this was the most important kinetic method available for reactions... 

The ultra-violet light induces electromagnetic excitation in molecules absorbing the laser energy, and by subsequently applying the principle of absorption spectroscopy, kinetic and spectroscopic information relating to the electronically excited states of various energetic molecules have been derived. The systems studied to-date include s-TNB, s-TNT, triphenyl-amine, and mono- as well as di-nitronaphthalenes (Ref 13, 14, 20, 21 28)... 

The theoretical relation, Ve — hv, has been abundantly checked in measurements of spectroscopy and physics but its direct application to complex molecules in chemical reactions has not been established. Bombardment of mercury atoms or other simple atoms at low pressures by electrons under controlled voltages causes the emission of monochromatic light at the wave lengths predicted by this formula. Moreover, the ionization potential, at which the electron is completely separated from its atom, corresponds directly to the wave length at which the discrete lines of the spectrum merge into a continuous spectrum. This continuous spectrum is due to the fact that the kinetic energy of the expelled electron and ion is not quantized. The close agreement between the ionization potential and the lowest frequency of continuous absorption, where ionization first starts, constitutes another proof of the relation Ve — hv. 

The relaxation of vibrationally excited species can frequently be observed directly by kinetic absorption spectroscopy, and it is rather surprising that this technique has provided so little detailed information about how energy is partitioned in chemical reactions, particularly when one remembers that experiments by Norrish and his co-workers [195] did much to initiate the present interest in this subject. Unfortunately, several conditions must be simultaneously fulfilled if the experiments are to succeed. These requirements are as follows ... 

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