Energy-band theory of Auger line shapes: SiliconL2,3VVand lithiumKVV

Abstract

It is shown that one-electron band theory predicts the experimentally observed $L_{2,3}\mathrm{VV}$ Auger line shape of silicon and the $\mathrm{KVV}$ line shape of lithium, provided that the partial densities of states are properly normalized for the atomic orbital (AO) basis used to calculate the matrix elements. This normalization, when combined with matrix-element effects, is responsible for the dominance of $p-p$ hole final states in the experimental spectra. The effect is equivalent to noting that with the atomic-orbital basis, the electronic charge is divided into atomic and overlap populations. Due to matrix-element effects, the latter does not contribute to the Auger process. Thus, Auger-electron spectroscopy is sensitive to the variation of the local atomic charge density across the valence band. Since the $s$ AO contributes more to the overlap (bonding) charge than the $p$ AO does, the $s$-like contribution is suppressed in the Auger line shape. The quality of the agreement with experiment suggests that the combined effects of the surface, many-body phenomena, and the distortion of the valence band in response to the core hole are small for the above spectra.