Simulation of keV clusters incident on gold targets

Using molecular dynamics (MD) simulations, Shapiro and Tombrello predicted that keV clusters containing a mixture of light and heavy atoms can eject a substantial fraction of their lighter atoms away from a target surface, a phenomenon they designate ``splash''. Recently, experiments by Diehnelt et al. and Brunelle et al. have shown evidence of ̄uorine and deuterium splash in systems of (NaF)nNa ‡ and deuterated valine, respectively, incident on gold targets. Although direct yields cannot be compared due to unknown ionization eciencies in the experiments, this paper describes further simulations which provide insight into the experimental systems. For the (NaF)nNa ‡ clusters, our results agree reasonably well with the observed trend in ̄uorine splash as a function of cluster energy but predict a di€erent dependence on cluster size. For the valine system, we ®nd the same dependence of the yield on cluster size as the experiment. Ó 1998 Elsevier Science B.V. All rights reserved. PACS: 31.13.Qg; 34.50.Dy; 36.40.Sx