Energy-loss spectra

Fig. VIII-10. (a) Intensity versus energy of scattered electron (inset shows LEED pattern) for a Rh(lll) surface covered with a monolayer of ethylidyne (CCH3), the structure of chemisorbed ethylene, (b) Auger electron spectrum, (c) High-resolution electron energy loss spectrum. [Reprinted with permission from G. A. Somoijai and B. E. Bent, Prog. Colloid Polym. ScL, 70, 38 (1985) (Ref. 6). Copyright 1985, Pergamon Press.]...

Figure Bl.6.9 Energy-loss spectrum of La203 showmg O K and La M white Ime resonances at the La edge [H].

Figure Bl.6.10 Energy-loss spectrum of 3.5 eV electrons specularly reflected from benzene absorbed on the rheniiun(l 11) surface [H]. Excitation of C-H vibrational modes appears at 100, 140 and 372 meV. Only modes with a changing electric dipole perpendicular to the surface are allowed for excitation in specular reflection. The great intensity of the out-of-plane C-H bending mode at 100 meV confimis that the plane of the molecule is parallel to the metal surface. Transitions at 43, 68 and 176 meV are associated with Rli-C and C-C vibrations.

Ion energy loss spectrum. A spectrum that shows the loss of translation energy among ions involved in ion/neutral reactions. 

Figure 2 Example of an energy-loss spectrum, illustrating zero loss, and low-loss valence band excitations and the inner shell edge. The onset at 111 eV identifies the material as beryllium. A scale change of 100X was introduced at 75 eV for display purposes.

Figure 1 Schematic of eiectron energy-loss scattering process for electrons of energy striking a Rh single-crystal surface with adsorbed CO molecules present. The actual energy-loss spectrum, due to excitation of CO vibrations, is shown also.

Cox, P. A., EgdeD, R. G., Eriksen, S. and Elavell, W. R. (1986) The high-resolution electron-energy-loss spectrum of TiO2(110)./. Electron Spectrosc. Relat. Phenom., 39, 117-126. 

Figure 10. Electron energy loss spectrum corresponding to Figure 9a. a, Si2, b, and c indicate the four energy windows 272-277 eV, 277-282 eV, 282-287 eV, and 287-292 eV, respectively.

Pb(110) at 77 K and warming to 140 K with (b) electron energy loss spectrum confirming the presence of surface hydroxyls at 160K when molecularly adsorbed water has desorbed. Both the oxide overlayer at Pb(110) and the atomically clean surface are unreactive to water. H abstraction was effected by transient Os states, which were also active in NH3 oxidation. (Reproduced from Refs. 40, 42). 

Figure 5.40. Illustration of an electron energy-loss spectrum showing the three typical regions a zero-loss peak, a low-loss peak and L and K edges.

Figure 5.45. Electron energy loss spectrum of MoNi-5 precipitate showing the Ni L23 edge at 855 eY. (Reproduced with permission of Penisson and Yystavel 2000.)...

Figure 11. Electron-energy-loss spectrum of crystalline boron nitride, showing the boron K-edge (at 190 eV) and the nitrogen K-edge (at 400 eV). The background intensity, delineated by the dashed curve arises from inelastic scattering by valence electrons. The hatched areas represent the measured values required for the quantitative analysis of boron ( see text) (50).

Structural Information from EELS. Besides yielding chemical composition, EELS is also capable of providing structural information on an atomic scale. It has been known (54) for some time that the fine-structure in the energy-loss spectrum close to an ionization edge reflects the energy dependence of the density of electronic states above the Fermi level. 

Fig. 3. (a) The inelastic scattering of electrons, (b) The energy loss spectrum for electron scattering by ethylene gas 8 near 90°. (Reproduced with permission from Kupperman and Ruff, 1962.)... 

Higher moments of the energy-loss spectrum such as straggling... 

Fig. 12. Electron energy-loss spectrum of uranophane solids containing 1300 and 6300 ppm Np. The double arrows on the figure are 176 eV and 184 eV wide, demonstrating the presence of Np in the solid (extracted from Buck et aL 2003).

We recognize that the present simple model for inelastic scattering does not account for certain details such as structure in the energy-loss spectrum due to plasmons (Davis and Lagally, 1981). Nevertheless, its simplicity and effectiveness bear out its practice. 

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