Segregation. Auger electron spectroscopy

Fig. 3.2 Characterization of Ptj Ni(hkr) surfaces with (a) Auger Electron Spectroscopy (AES) (b) LEIS (revealed complete segregation of Pt for aU three orientations and the formation of the Pt-skin structure (c) UPS (confirmed that the position of d-band center is structure sensitive (d-f) LEED the Pt3Ni(l 11) surface exhibits a (1 X 1) pattern, Pt3Ni(100) has a (1 x 5) reconstruct pattern, and Pt3Ni(110) exhibits (1 x 2) periodicity. Reprinted with permission from [23], copyright 2007 by American Association for the Advancement of Science...

The author discusses selected examples of Auger electron spectroscopy applications to the study of the role played by sulfur adsorption in the field of heterogeneous catalysis and its implication for the metallurgical problems of segregation, surface self-diffusion and temper embrittlement. 

Surface segregation is normally studied experimentally by the surface-sensitive techniques of photoelectron spectroscopy (ESCA, XPS), Auger electron spectroscopy and atom probe. 

Leiro, M. Heinonen, J. Juhanoja, X-ray photoelectron and Auger electron spectroscopies and surface segregations in Pd-Rh and Pd-Ru membrane catalysts. Surf. Int. Anal. 1995, 23(1), 50-54. 

Ueb] SEM, Auger electron spectroscopy 15 mass% Cr, < 0.03 mass% N, surface segregation of nitrides... 

Auger spectroscopy Auger electron spectroscopy is a powerful surface analysis technique, as the analytical signals come from the top few monolayer of the specimen. In this technique, a primary beam of electrons is used to produce inner shell vacancies in atoms of the specimen. This method has been used for the determination of sulfur, e.g., on GaAs surfaces and to study sulfur surface segregation in Ni-Al solid solutions and the adsorption on a GaAs (001) surface by hydrogen sulfide exposure and heat treatment. 

Paj] Auger Electron Spectroscopy, phosphorus segregation 825-1100°C, < 0.35 mass% C, < 0.2 mass% P... 

COW, 2002COW] Auger Electron Spectroscopy, phosphorus segregation < 600°C, 0.002 mass% C, 0.06 mass% P, diffusion measurement... 

In the reduced catalyst CaO has been shown by Auger electron spectroscopy [162] and X-ray photoelectron spectroscopy [52] to remain in its oxidic state. Chemisorption measurements [163] and X-ray powder diffraction studies [164] show that during the reduction CaO segregate to the space between the Fe crystallites. 

The segregation of K to the surface has been demonstrated by chemisorption measurements [207,220], by scanning Auger electron spectroscopy [52,209-211], by X-ray photoelectron spectroscopy [208], and by electron microscopy [92]. Single crystal studies of K overlayers on Fe(l 10) demonstrate that K is not a structural promoter [221] and that K may even reduce the ability of A1 to disperse Fe [221]. 

For both samples the Pd surface segregation is clearly shown by electron spectroscopies, AES or XPS. The peaks characteristic of Pd (PdMvv Auger peak... 

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