Photoelectron spectroscopy oxide surface

A. A. Mirzaei, H. R. Shaterian, and M. Kaykhaii, The X-ray photoelectron spectroscopy of surface composition of aged mixed copper manganese oxide catalysts, Applied Surface Science, vol. 239, no. 2, pp. 246—254, 2005. 

XPS X-ray photoelectron spectroscopy [131-137] Monoenergetic x-rays eject electrons from various atomic levels the electron energy spectrum is measured Surface composition, oxidation state... 

X-ray photoelectron spectroscopy (XPS), also called electron spectroscopy for chemical analysis (ESCA), is described in section Bl.25,2.1. The most connnonly employed x-rays are the Mg Ka (1253.6 eV) and the A1 Ka (1486.6 eV) lines, which are produced from a standard x-ray tube. Peaks are seen in XPS spectra that correspond to the bound core-level electrons in the material. The intensity of each peak is proportional to the abundance of the emitting atoms in the near-surface region, while the precise binding energy of each peak depends on the chemical oxidation state and local enviromnent of the emitting atoms. The Perkin-Elmer XPS handbook contains sample spectra of each element and bindmg energies for certain compounds [58]. 

An important property of the surface behaviour of oxides which contain transition metal ions having a number of possible valencies can be revealed by X-ray induced photoelectron spectroscopy. The energy spectrum of tlrese electrons give a direct measure of the binding energies of the valence electrons on the metal ions, from which the charge state can be deduced (Gunarsekaran et al., 1994). 

Surface analysis has made enormous contributions to the field of adhesion science. It enabled investigators to probe fundamental aspects of adhesion such as the composition of anodic oxides on metals, the surface composition of polymers that have been pretreated by etching, the nature of reactions occurring at the interface between a primer and a substrate or between a primer and an adhesive, and the orientation of molecules adsorbed onto substrates. Surface analysis has also enabled adhesion scientists to determine the mechanisms responsible for failure of adhesive bonds, especially after exposure to aggressive environments. The objective of this chapter is to review the principals of surface analysis techniques including attenuated total reflection (ATR) and reflection-absorption (RAIR) infrared spectroscopy. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) and to present examples of the application of each technique to important problems in adhesion science. 

M. Peuckert, and H.P. Bonzel, Characterization of oxidized platinum surfaces by X-ray photoelectron spectroscopy, Surf. Sci. 145, 239-259 (1984). 

In the case of selective oxidation catalysis, the use of spectroscopy has provided critical Information about surface and solid state mechanisms. As Is well known( ), some of the most effective catalysts for selective oxidation of olefins are those based on bismuth molybdates. The Industrial significance of these catalysts stems from their unique ability to oxidize propylene and ammonia to acrylonitrile at high selectivity. Several key features of the surface mechanism of this catalytic process have recently been descrlbed(3-A). However, an understanding of the solid state transformations which occur on the catalyst surface or within the catalyst bulk under reaction conditions can only be deduced Indirectly by traditional probe molecule approaches. Direct Insights Into catalyst dynamics require the use of techniques which can probe the solid directly, preferably under reaction conditions. We have, therefore, examined several catalytlcally Important surface and solid state processes of bismuth molybdate based catalysts using multiple spectroscopic techniques Including Raman and Infrared spectroscopies, x-ray and neutron diffraction, and photoelectron spectroscopy. 

M. W. Roberts, The nature and reactivity of chemisorbed oxygen and oxide overlayers at metal surfaces as revealed by photoelectron spectroscopy, in Structure and Reactivity of Surfaces, ed. C. Morterra, A. Zechina and G. Costa, Elsevier, Amsterdam, 1989, p. 787. 

The structure of [Ir2dcbmi(CO)4] (424) is reported.680 The binuclear compounds were all oxidized around +0.1 V vs. SCE, with the oxidation potential dependent on the solvent.681 Oxidation of [NBu4][Ir2(dcbmi)(CO)4] results in growth of a conducting film on the surface. The partially oxidized material [NBu4]0.5[Ir2(dcbmi)(CO)4] has been characterized by X-ray photoelectron spectroscopy. 

R. Kotz reviews the application of the most powerful surface physics technique, photoelectron spectroscopy, for the elucidation of the composition of electrodes. He exemplifies the potential of this technique for materials which play a key role in electrochemical oxidation processes or are used in some other electrochemical process. 

Cobalt is strongly adsorbed by Mn oxides. There are close relationships between Co and the easily reducible fraction of Mn (Mn oxides) in soils (Jarvis, 1984) and will be in detail discussed in next chapter. Cobalt is frequently accumulated in Mn nodules in soils (Mckenzie, 1975). It was suggested that the Co2+ ion was first sorbed, then slowly oxidized to Co3+ and became incorporated into the surface layers of the crystal lattice, releasing the Mn2+ ion into the solution (Bums, 1976 Mckenzie, 1975). X-ray photoelectron spectroscopy showed that Co3+ was present on the surface of bimessite after the sorption of the Co2+ ions took place (Murray and Dillard, 1979). Traina and Donor (1985) suggested that the Mn release during Co2+ sorption resulted not only from the oxidation of Co2+ to Co3+, but also... 

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