Electron transfer on oxygen-covered Ag(110) and Al(111) surfaces: work function versus local electronic effects

Abstract

The results of a study of changes in electron capture and loss rates in the interaction of fluorine atoms and anions with oxygen-covered Al(111) and Ag(110) surfaces are reported for a wide range of coverages. A strong decrease in F − formation is observed. The magnitude of this decrease shows that the capture rates are much smaller than those expected on the basis of work-function changes. The observed decrease is assigned to changes in local electronic structure in the vicinity of the adsorbate site and modifications in positions and widths of the anion levels. It was found that for incident F − and F°, the final F − fractions are different, indicating that the memory of the initial charge state is not lost as in the clean metal case. This difference indicates that the electron-loss rate is smaller in the presence of oxygen. An incident-energy dependence of the loss process is observed.