Siegbahn chemical shift

Studies by Short et al. (260) of the intensity of the white line of Pt on Ti02 indicate that the charge transfer from metal to support is essentially quite small, in accordance with XPS data. In fact, no Siegbahn chemical shift of the metal in the SMSI state has been observed (128a), nor are there XPS indications for electron transfer from titania to the metal (55, 257,290). 

Figure 8.14 The monochromatized AlATa carbon Is X-ray photoelectron spectrum of ethyltrifluoroacetate showing the chemical shifts relative to an ionization energy of 291.2 eV (Reproduced, with permission, from Gelius, U., Basilier, E., Svensson, S., Bergmark, T. and Siegbahn, K., J. Electron Spectrosc., 2, 405, 1974)...

One other very important attribute of photoemitted electrons is the dependence of their kinetic energy on chemical environment of the atom from which they originate. This feature of the photoemission process is called the chemical shift of and is the basis for chemical information about the sample. In fact, this feature of the xps experiment, first observed by Siegbahn in 1958 for a copper oxide ovedayer on a copper surface, led to his original nomenclature for this technique of electron spectroscopy for chemical analysis or esca. 

By using the XPS chemical shifts and the charge potential model of Siegbahn et al (1 ) to calculate the net charge distribution, as described previously, we verify that the N atom is the primary reaction site for the PIM adsorbate (12). 

Figure 14.16 ESCA spectrum showing the chemical shifts of carbon and oxygen atoms in methyl acetate. (From Siegbahn, copyright 1973 with permission from Elsevier.)...

P. Kelfve, B. Blomster, H. Siegbahn, K. Siegbahn, E. Sanhueza and O. Goscinski Chemical Shifts of Auger Electron Lines and Electron Binding Energies in Free Molecules. Silicon Compounds Physica Scripta 21, 75 (1980). 

Prof. Kai Siegbahn of Uppsala University, Uppsala, Sweden, is the person who gave birth to XPS and finessed it into a powerful technique in a short time, after his observation and discovery of chemical shift in sodium thiosulfate. The publications of his two books [2,3], one mainly on solids and the other on free molecules established XPS as a versatile analytical tool applicable to a large field of science. Every month more than a hundred publications appear in which XPS is used to elucidate the properties of the surface or bulk. Carlson [4] gives a comprehensive account of the XPS technique in his book. On account of the great impact XPS has made to scientific progress. Prof. K. Siegbahn was awarded the Nobel prize for Physics in 1981. 

Figure 13.2—Simplified schematic of an atom showing the origin, and the Siegbahn nomenclature, of some fluorescence radiation processes caused by impact of a photon having a high energy. The position of the spectral line is not significantly influenced by the chemical combination in which the atom is found. For example, the Kat line from sulphur is observed at 0.5348 nm for S + and at 0.5350 nm for S°, yielding a shift of 1 eV, which is comparable to the natural line width for X-rays.

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