Electron ejection

AES ARABS Auger electron spectroscopy [77, 112-114, 117] Angle-resolved AES [85, 115] An incident high-energy electron ejects an inner electron from an atom an outer electron (e.g., L) falls into the vacancy and the released energy is given to an ejected Auger electron Surface composition... 

Other techniques in which incident photons excite the surface to produce detected electrons are also Hsted in Table 1. X-ray photoelectron Spectroscopy (xps), which is also known as electron spectroscopy for chemical analysis (esca), is based on the use of x-rays which stimulate atomic core level electron ejection for elemental composition information. Ultraviolet photoelectron spectroscopy (ups) is similar but uses ultraviolet photons instead of x-rays to probe atomic valence level electrons. Photons are used to stimulate desorption of ions in photon stimulated ion angular distribution (psd). Inverse photoemission (ip) occurs when electrons incident on a surface result in photon emission which is then detected. 

Any material which can form a color center contains two types of precursors as shown in Figure 2a. The hole center precursor is an atom, ion, molecule, impurity, or other defect which contains two paired electrons, one of which can be ejected by irradiation, leaving behind a hole center (Fig. 2b). The electron center precursor is an atom, ion, etc, which can produce an electron center by trapping the electron ejected from the hole center precursor. A hole and an electron center are thus formed simultaneously. Either or both can be the color center. Almost all materials have hole center precursors. If there is no electron center precursor, however, the displaced electron returns to its original place and the material remains unchanged. 

In electron spectroscopic techniques - among which XPS is the most important -analysis of the energies of electrons ejected from a surface is central. Nowadays universally employed is the concentric hemispherical analyzer (CHA). 

Inasmuch as the Auger effect can occur in any atom having a single appropriate electron hole, satellite lines are produced by electron excitation also. With this mode of excitation, they will be produced also when the Auger effect does not occur provided a single incident electron ejects two electrons from the atom. 

The kinetic energy of the electron ejected from the metal increases linearly with the frequency of the incident radiation according to Eq. 5. 

The most common types of radiation emitted by radioactive nuclei are a particles (the nuclei of helium atoms), /3 particles (fast electrons ejected from the nucleus), and 7 rays (high-frequency electromagnetic radiation). 

Semi-Classical Pictures of Non-Adiabatic Induced Electron Ejection in Molecular Anions... 

There exist a series of beautiful spectroscopy experiments that have been carried out over a number of years in the Lineberger (1), Brauman (2), and Beauchamp (3) laboratories in which electronically stable negative molecular ions prepared in excited vibrational-rotational states are observed to eject their extra electron. For the anions considered in those experiments, it is unlikely that the anion and neutral-molecule potential energy surfaces undergo crossings at geometries accessed by their vibrational motions in these experiments, so it is believed that the mechanism of electron ejection must involve vibration-rotation... 

Dipole-bound anions (5a, 4f) in which the extra electron is attracted primarily by the dipole force field of the polar molecule and for which rotation-to-electronic coupling is most important in inducing electron ejection. 

NH (X n) for which (4d) vibration of the N-H bond couples only weakly to the non-bonding 2pn orbital and for which rotation-to-electronic coupling can be dominant in causing electron ejection for high rotational levels. 

Our calculations have been successful in interpreting trends that are seen in the experimentally observed rates of electron ejection. However, until now, we have not had a clear physical picture of the energy and momentum (or angular momentum) balancing events that accompany such non BO processes. It is the purpose of this paper to enhance our understanding of these events by recasting the rate equations in ways that are more classical in nature (and hence hopefully more physically clear). This is done by... 

Ej -Ef, and multiplied by the density of states p(E) appropriate to the electron ejected with kinetic energy E. 

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