Influence of surface band gaps on the lifetimes of charge transfer states

Using a first principles electronic structure method, we investigate how a band gap in the surface projected density of states of a noble metal influences the resonant tunneling lifetime of an atomic level near the surface. Comparing Li atoms outside Cu(111), where the Li 2s level is within the gap, with Cu(001), where the Li 2s level is below the gap, reveals that the lifetime of the ionization level of Li is longer on Cu(111). This difference is caused both by the decreased final state phase space for the tunneling electron on Cu(111) and by a reduction in intra-atomic hybridization in Li outside a surface whose band gap encompasses the ionization level. Our results are consistent with previous experiments and theory that predict a similar trend for the ionization level of Cs above Cu(111) and Cu(001). 2006 Elsevier B.V. All rights reserved.