CHEMICAL INFORMATION IN AUGER-SPECTROSCOPY

It has long been suggested that Auger spectroscopy, the most widely used surface analytical technique, should be capable of yielding chemical information in addition to its normal role for surface elemental analysis. However, to date this application has only been minimally developed. The Auger process, in contrast to that of photoelectron spectroscopy, involves a direct coupling between core and valence states and, as a result, yields spectra which are sensitive to the valence electronic structure local to a specific atom (i.e., its local chemical environment). We have experimentally and theoretically probed this aspect of Auger spectra through the use of a coherent set of molecules investigated both in the gas and solid phases. The relative peak positions are directly related to the ionization potentials of the various valence orbitals while the peak intensities are a direct measure of the variation of local atomic (as opposed to bonding) charge populations across the valence orbitals. Moreover, in the condensed phase, where intermolecular bonding operates through a specific atom in the molecule (i.e., 0 in solid H20), the Auger spectra clearly show this local effect. © 1979, American Chemical Society. All rights reserved.