Simulation of sputtering induced by high energy gold clusters

Recently Andersen et al. reported exceptionally large nonlinear sputtering yields following the bombardment of gold targets with small, high energy gold clusters (H.H. Andersen, A. Brunelle, S. Della-Negra, J. Depauw, Y. LeBeyec, Phys. Rev. Lett. 80 (1998) 5433). Nonlinearities up to ∼1000% were observed for Au_5 clusters with a total energy of 800 keV. We have carried out molecular dynamics simulations on a massively parallel computer to model the Au_n → Au system. The results suggest that both collisional and thermal spike mechanisms contribute to the large nonlinear yields observed by Andersen et al. Our simulations also indicate that sputtering statistics are very important at high cluster bombarding energies. A substantial fraction of the simulated impacts produce no sputtered atoms, while individual sputtering events producing very large numbers of sputtered atoms contribute significantly to the total sputtering yield at high energy