Ag(100) surface density of states probed by metastable deexcitation spectroscopy: A comparison between experiment and theory

The metastable deexcitation spectrum of Ag(100) is measured and information on the effective density of states probed by the metastable atom is obtained by deconvolution of the experimental spectrum, under the hypothesis that it reflects the self-convolution of the surface density of states. Layer resolved semi-empirical LCAO calculations are compared to the deconvolution curve, showing poor agreement as far as the branching ratios of sp versus d contributions are concerned. The agreement between theory and experiment strongly improves if an energy dependent exponential decay factor is included in the first layer calculated density of states to account for the energy dependent increased overlap between electronic states of the solid and metastable atom outside the surface.