Effect of intra-atomic Coulomb repulsion on charge transfer in atom scattering on metal surfaces

Abstract

Charge transfer in atom scattering on metal surfaces is usually described employing the time-dependent Anderson model. In the framework of this model, the electron hopping matrix element is assumed independent of the intra-atomic Coulomb repulsion and the occupation numbers of the adatom orbital. In the present paper, the latter assumption is relaxed. The occupation number dependence of the hopping matrix element is shown to describe the possibility of the formation of neutral, positive and negative ions in a single approach. The connection between the exact quantum mechanical result and the phenomenological master equation approach is outlined. The latter is shown to be valid for typical atom velocities, ν = 0.005−0.001 au, and is most efficient for numerical calculations. Calculated results are used to analyze experimental data for the scattering of alkali atoms on metal surfaces.