NEAR-THRESHOLD ELECTRON-EMISSION FROM SLOW CLUSTER-IMPACT ON CLEAN GOLD

Atomically clean polycrystalline gold was bombarded by slow cluster io ns (N2)n+ (n less-than-or-equal-to 100), Ne(n)+ (n less-than-or-equal- to 100) and C60q (q less-than-ro-equal-to + 5; - 1) of kinetic energie s 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 d ifferent electron yields were found for different cluster species of t he same velocity and similar mass, which is attributed to different pa rtitioning of the initial cluster kinetic energy among a) inelastic bi nary collision processes involving cluster constituents and surface at oms, and b) vibrational excitation (when possible). For (N2)n cluster ions clear evidence of a non-linear behaviour (i.e. increasing electro n emission per cluster constituent with increasing cluster size) was o bserved.