Electronic states at the surfaces of crystals

Abstract

In the present paper application of the work of paper I is made to a specific problem, namely the excitation of an adsorbed atom by the surface electrons of the underlying metal. It is shown that the corresponding mean life-time in a typical excited level is 3·7 × 10−11 sec., which is comparable with the value 1·7 × 10−12 sec. for deactivation by the conduction electrons when the Brillouin zone is only partly filled. Thus, though this is an essentially surface phenomenon, the effect of the surface electrons is begligible. This suggests that their effect can, in general, only become appreciable in semi-conductors or insulators.