Transition elements, Auger spectrum

There are at least four kinds of information available from an Auger spectrum. The simplest and by far most frequently used is qualitative information, indicating which elements are present within the sampling volume of the measurement. Next there is quantitative information, which requires a little more care during acquisition to make it extractable, and a little more effort to extract it, but which tells how much of each of the elements is present. Third, there is chemical information which shows the chemical state in which these elements are present. Last, but by far the least used, there is information on the electronic structure of the material, such as the valance-band density of states that is folded into the line shape of transitions involving valance-band electrons. There are considerations to keep in mind in extracting each of these kinds of information. 

Figure Bl.25.6. Energy spectrum of electrons coming off a surface irradiated with a primary electron beam. Electrons have lost energy to vibrations and electronic transitions (loss electrons), to collective excitations of the electron sea (plasmons) and to all kinds of inelastic process (secondary electrons). The element-specific Auger electrons appear as small peaks on an intense background and are more visible in a derivative spectrum.

The carbon spectrum at 790 K is an example of the ability of the catalyst to purify itself. Under these conditions, the carbon compounds are present as elemental carbon with a graphitic valence structure. The wide peak at 284.8 eV and a change in the line shape of the C KW Auger transition (not shown here) indicate a transformation of the graphitic structure to a type of carbon which is susceptible... 

As was the case for XPS, to understand the correct use of sensitivity factors in AES it is necessary to consider briefly the origin of the various terms that give rise to the Auger intensity in the electron spectrum. The intensity of emission of Auger electrons originating from a particular electronic transition in a uniformly illuminated specimen of element a is... 

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