Auger analytical potential

The last chapter (chapter 109) is by D.R. Chopra on appearance potential spectroscopy (APS), which measures the probability for electronic excitation of a core level as a function of the incident electron energy. APS is based on a two-electron excita-tion/relaxation process and gives information on the density of unoccupied states. APS is a complementary technique to the more common Auger electron spectroscopy and X-ray photoelectron spectroscopy, and it also yields information on chemical bonding, near-neighbor configuration in the surface layer, and the chemical constituents. The author believes that when the different aspects of APS are fully exploited this technique will be accepted as a popular analytical tool for the material characterization of surfaces. 

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