Approximate approach to metastable He deexcitation on metal surfaces

In this paper a simple approximate approach is used to reproduce the ab initio results for the deexcitation spectral profiles of a metastable helium atom at different distances from a surface. The main quantities of our method are the spin dependent local density of states (LDOS) around the excited helium atom. We show that the extension of the spherical volumes around the atom in which we evaluate the LDOS are the only relevant parameters in this approach and they do not depend on the atom-surface distance.