Molecular dynamics simulations of inner shell electronic energy losses in cluster-surface collisions

Abstract

Previous molecular dynamics simulations have predicted that in energetic cluster-surface collisions atoms can be core-excited leading to Auger transitions outside the target [5]. However, in these previous simulations the inelastic energy losses accompanying core-excitations were not taken into account. In our simulations a simple critical distance of approach to detect inner-shell excitations is used. Energy is removed from atoms in a single time step by moving the atoms apart from each other, taking away potential energy. Molecular dynamics simulations are carried out for 63-atom Al clusters and composite Al_(38)Au_(25)clusters incident on Au(100) targets and Au(111) targets. Each event is simulated with and without inelastic losses. Incident cluster energies ranged from 30 to 100 keV. Our results indicate a threshold for significant inelastic loss effects at approximately 70 keV/cluster, i.e., about 1 keV/atom. Above the threshold energy region, sputtered atom and ejected-cluster atom energy distributions were affected substantially.

Additional details