Electronic energy spectra

Figures The NIE), dN E)/dE, dEN E/dE. and EN E) forms of secondary electron energy spectra from a slightly contaminated Fe surface.

Wang Jianqi, 1992. Introduction to Electron Energy Spectra (XPS/XAES/UPS). Beijing Defence Industrial Press... 

In 1985. two research institutions (IBM and AT T Bell Laboratories) reported that electrons can travel through a semiconductor without being slowed by collisions (ballistically). The report was based upon experimental data showing a ballistic peak in the electron energy spectra of gallium arsenide (GaAs) test devices. Tins is reported in more detail in article on Arsenic. 

A quantum mechanical calculation of the Penning electron energy spectra for the two different potentials would be quite interesting. A comparison with recent high-resolution results (2) would give an independent experimental check on the existence or nonexistence of the maximum in the potential. 

Moxom, J., Laricchia, G., Charlton, M., Jones, G.O. and Kover, A. (1992). Ejected-electron energy spectra in low energy positron-argon collisions. J. Phys. B At. Mol. Opt. Phys. 25 L613-L619. 

Fig. 4.11. One-electron energy spectra derived in coincidence with double ionization derived from (4.31) for various noble gases. Solid line He at laser intensity I = 8 x 1014W/cm2, dashed line Ne at / = 6 x 1014 W/cm2, dotted line Ar at I = 2.5 x 1014 W/cm2. The parameters correspond to the experimental data of [51]...

Figure 3 demonstrates the electron spectrometer part of a depth-resolved conversion electron MOssbauer spectrometer specially designed for such measurements in our laboratory (10, 11). The electron spectrometer is of the cylindrical mirror type back-scattered K conversion electrons from resonantly excited Fe nuclei are resolved by the electrostatic field between the inner and outer cylinders (cylindrical mirror analyzer) and then detected by a ceramic semiconductor detector (ceratron). The electron energy spectra taken with this spectrometer indicate that peaks of 7.3-keV K conversion electrons, 6.3-keV KLM Auger electrons, 5.6-keV KLL Auger electrons, etc., can be resolved well, with energy resolution better than 4%. 

Evidence for this mechanism consists of structure in electron energy spectra that cannot be explained by ionic states of the parent molecule but can be explained in terms of the ionic states of a fragment. 

Extensive ion yield spectra, mass spectra, and ion-ion coincidence data have been acquired for carbon monoxide at both the carbon and oxygen K ionization edges. Dissociative multiple ionization efficiencies, ion branching ratios, and kinetic energy distributions were derived. The results were related to electron energy spectra and potential energy curves for states of (Hitchcock et al. 1988). 

SYNCHROTRON INVESTIGATIONS OF ELECTRON-ENERGY SPECTRA IN SILICON NANOSTRUCTURES... 

The electron energy spectra of a clean Fe/W(l 10) film with a thickness of about 20 A and of O on such FeAV(l 10) films with an oxygen exposure of 3 L are shown in Fig. 5.22. The structure at high kinetic energies is caused by Fe kI electrons near the Fermi level. After dosing oxygen to the iron surface, the emission of these electrons is drastically reduced. 

The orbiting and the classical and semiclassical impact parameter models have been used to interpret inelastic scattering data in chemiionization, the dependence of ionization cross-section on collision energy and electron energy spectra, in order to gain information about the potential curves, V and V, and the autoionization width, (/ ). 

The chemi-ionization reactions of He with other open shell atoms such as Na and Hg show analogous characteristics of strongly bound V potentials, an inverse dependence of ionization cross-section on collision energy and markedly broadmed electron energy spectra. ... 

ELECTRON ENERGY SPECTRA OF CRYSTALLINE AND GLASSY ARSENIC CHALCOGENIDES ... 

J. Y. Wada and H. Heil, Electron energy spectra in neon, xenon, and helium-neon laser discharges, J. Quantum Electronics QE-1(8), 327-335 (1965). 

Detailed reviews of the band structure of interstitial carbides were made by Schwarz,0 l Calais,[ Neckel,l J Ivanovsky, and Redinger. The band structure can be summarized as follows. The electronic energy spectra of these carbides are similar and contain bands of C2s, C2p-Md,s, and Md,s,p states (M = metal). When the valence concentration (VEC) in the elementary cell of the carbide is 8 (TiC, ZrC, and HfC), the Fermi level is found in the region of the density-of-state minimum between p-d and fif-like bands. With VEC > 8 (carbides of Groups V and VI), the Fermi level is in the low-energy region of the metal states band. 

The situation is more complicated if several autoionizing states in He are excited by low-energy ion impact such that postcollision interaction leads to interferences between transitions from these states. As an example Figure 20 shows coincident electron energy spectra from Li" + He collisions. 

Figure 29. Electron energy spectra from He-He collisions at collision energies of (a) 200 eV and (b) 500 eV. Electrons are due to autoionization of quasimolecular states, correlating to two singly excited He atoms in the separated atom limit. The separated atom states are indicated in part (b).

Another system that recently attracted much attention in connection with quasimolecular electron emission is the (LiHe) collision complex. Electron energy spectra due to low energy Li + He collisions were measured by Yagishita et for electron emission angles between 20 and 150°... 

Table 3.23 gives the surface compositions of AllO catalyst before and after the reduction as well as after the heat-resisting tests, which were obtained by the electron energy spectra (AES) and XPS (probing depth of 2 x 10 m). Before reduction, the number of iron atoms on the surface is only 5.4%, while the atomic compositions of the promoters are less than 10% in the bulk. However, on surface, the concentrations of promoters are above 50% no matter before or after reduction, or after the heat-resisting tests. It is clearly indicated that the phenomenon of surface segregation or surface enrichment of the promoters is commonly present and comparatively serious for fused-iron catalysts of ammonia synthesis. The surface states of catalysts are not only decided by their chemical composition and preparation method, but also connected with the reduction and use conditions. 

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