Femtosecond Neutralization Dynamics in Cluster-Solid Surface Collisions

Experimental results for the relative electron emission yields γ(N) of charged clusters colliding at low energies with different surfaces are presented. For fixed collision energy a remarkable cluster size dependence of γ(N) is obtained using highly oriented pyrolytic graphite as target. By studying theoretically the collision process within a microscopic model we find that the nonadiabatic survival probability of the charged clusters shows the same behavior as γ(N). Thus, γ(N) reflects the femtosecond neutralization dynamics during the collision, which may result in damped St\"uckelberg oscillations for targets with narrow densities of states.