The graphite Core-Valence-Valence Auger Spectrum

The graphite core–valence–valence (CVV) Auger spectrum is analysed, within a one particle approximation, by comparison to the X-ray excited valence band (VB) photoemission spectrum, whose structure is well understood in terms of the graphite density of states (DOS). The aim is to identify the electron states originating the components into which the CVV spectrum is resolved by double differentiation. Contributions assigned to self-folds of VB photoemission features and hence due to transitions coupling electrons from the same DOS feature, dominate the spectrum away from the middle region, while folds between different features are important in the middle region. A single particle approximation proves to be adequate to account for the low binding energy, mostly p-like, part of the spectrum. It brakes down however in the high binding energy, mainly s-like, region where spectral distortion is ascribed to a nonnegligible (2 eV) Coulomb repulsion between final state holes of s-symmetry