HIGH-RESOLUTION AUGER-SPECTROSCOPY APPLIED TO METALS AND ALLOYS

Auger electron spectroscopy (AES) is fundamentally a spectroscopy of e xcited states, so that the resulting information is complementary to t hat from X-ray photoelectron spectroscopy (XPS). Consequently, high-re solution AES has received a great deal of theoretical and experimental attention in recent years. In metals and their alloys, much of the in terest has involved valence band spectra, which are explained in terms of the quasi-atomic model of final-state screening, especially in clo sed d-shell metals, such as Cu and Ag. In open shell metals, such as N i and Pd, however, the shapes of the valence band spectra are often am biguous. Core level spectra. which might reduce uncertainties, are oft en complex and not readily interpretable. It is shown that the high-en ergy LMM spectra of the 4d metals and their alloys are sufficiently si mple in form and narrow to permit unambiguous comparisons with quasi-a tomic theories. The exploitation of the experimental systematics of th e LMM Auger parameter elucidates screening mechanisms as well as the n ature of d-band holes and the extension of the analysis to the 3d and 5d metals indicates similar results. Application to metallic alloys cl arifies the electronic structure changes; examples of Pd-based alloys are presented. Consideration of the lineshapes of these spectra reveal s a satellite structure which can, with considerable certainty, be ide ntified with shake-up processes associated with 4d-band spectator vaca ncies.