Interaction time dependence of electron tunneling processes between an atom and a surface

Results of a study of electron transfer processes in the interaction of flu orine and hydrogen with Ag(111) are reported for a wide range of interactio n times. For long interaction limes the yield of H-, resulting from resonan t electron exchange, is larger than expected for a jelliumlike metal surfac e with a similar work function. For short interaction times, the yields fol low the trend for jelliumlike surfaces. These results confirm the predictio ns of the theoretical work [Borisov et nl. Phys. Rev. Lett. 80, 1996 (1998) ] on electron transfer on surfaces with an L band gap; In the case of F-, s ignificant effects were, however, not observed. [S0031-9007(99)09233-9].