Electron tunneling rates between atoms and surfaces covered by dielectric films

Using the complex scaling method, we have investigated how the energy shift and broadening of atomic levels near metal surfaces is modified when thin dielectric films are adsorbed on the surface. The calculation shows that dielectric films can introduce a significant tunneling barrier which can drastically reduce the widths of the atomic levels. Also, the atomic level shift can be strongly modified. Near the metal/film and film/vacuum interface non-image-like shifts occur which can be sufficiently strong to alter the charge transfer.