Near-Threshold Electron Emission from Slow Cluster Impact on Clean Gold

Abstract

Atomically clean polycrystalline gold was bombarded by slow cluster ions (N2)n+ (n ⩽ 100), Nen+ (n ⩽ 100) and C60q (q ⩽ + 5; - 1) of kinetic energies from the apparent electron emission thresholds up to 6 kV times the cluster charge (qe). The resulting electron emission yields have been derived from the corresponding electron emission statistics. Grossly different electron yields were found for different cluster species of the same velocity and similar mass, which is attributed to different partitioning of the initial cluster kinetic energy among a) inelastic binary collision processes involving cluster constituents and surface atoms, and b) vibrational excitation (when possible). For (N2)n cluster ions clear evidence of a non-linear behaviour (i.e. increasing electron emission per cluster constituent with increasing cluster size) was observed.