Valence electron kinetic energy

Chemical binding is promoted by the lowering of valence-electron kinetic energy and hence by the quenching of orbital angular momentum. 

Photoelectron spectroscopy is a highly surface sensitive technique because of the inelastic mean free path of the photoelectrons Ae, which depends on the electron kinetic energy Ekin and has typical values of 0.2-3nm [31,37,38]. Determination of Schottky barrier heights b, or valence band discontinuities AEyB, can be performed by following the evolution of the position of the valence band maxima with respect to the Fermi level of substrate and overlayer with increasing thickness of the overlayer. For layer-by-layer growth the attenuation of the substrate intensities is given by the inelastic... 

The valence band electronic structure of the top few atomic layers can be determined from the variation in photoelectron intensity as a function of electron kinetic energy and incident photon energy. 

The occupancy of the free-electron valence band, built mainly from s- and p-valence atomic orbitals can be considered close to constant with one electron per metal atom. This is due to hybridization of the atomic orbitals by formation of the metal atom-metal atom bonds. Within free electron theory, its energy is mainly determined by the density of the metal atoms [25], When an adatom adsorbs, the charge density on the adatom adjusts so that the chemical potential on the adatom becomes equal to that at the surface. When the adatom orbital is half occupied, this results in an attractive interaction because of electron transfer to the adsorbate. When the adatom orbital is doubly occupied, the interaction becomes repulsive, because of the increase in electron kinetic energy due to the PauH electron exclusion rule [25], The interaction with adatoms is rather independent of the coordination of the adatom with the surface. 

X-ray photoelectron spectroscopy (XPS) is among the most frequently used surface chemical characterization teclmiques. Several excellent books on XPS are available [1, 2, 3, 4, 5, 6 and 7], XPS is based on the photoelectric effect an atom absorbs a photon of energy hv from an x-ray source next, a core or valence electron with bindmg energy is ejected with kinetic energy (figure Bl.25.1) ... 

Flere we distinguish between nuclear coordinates R and electronic coordinates r is the single-particle kinetic energy operator, and Vp is the total pseudopotential operator for the interaction between the valence electrons and the combined nucleus + frozen core electrons. The electron-electron and micleus-micleus Coulomb interactions are easily recognized, and the remaining tenu electronic exchange and correlation... 

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