Neutralization rates of slow highly charged Ar ions in single and double scattering from a Au(111) surface

Slow (nu approximate to 0.06 a.u.) highly charged Arq+ (6 less than or equa l to q less than or equal to 13) are scattered from a prepared Au(111) surf ace. At large angle scattering geometry with an incident angle psi = 25 deg rees and a scattered angle theta = 75 degrees a double peak structure is ob served in the energy spectrum. The two peaks correspond to two well defined scattering trajectories, where the ions undergo single or double collision s at one or two Au atoms at the surface, respectively. Previously it was re ported that the yield of multiply charged scattered ions (MCSI) increases b y nearly three orders of magnitude for single collisions when the Ar ions c arry initial L-shell vacancies. This strong shell-effect is partly suppress ed for ions experiencing double collisions, which indicates L-shell filling due to two collisions and a longer interaction time.