Energetic impact of size-selected metal cluster ions on graphite

We have investigated the impact of size-selected metal cluster ions (Ag-n(-)) on a covalently bonded substrate (graphite) over the energy range 15-1500 eV by a combination of scanning tunneling microscopy and molecular dynamics simulations. The key result is that the fate of the cluster (penetration into the surface versus diffusion and aggregation on the surface), at intermediate energies, depends on the lateral localization of the cluster kinetic energy at specific surface sites and thus, for small clusters, on the orientation of the cluster and the target substrate site. [S0031-9007(98)07519-X].