Molecular dynamics simulations of sputtering involving clusters

Abstract

In this paper we reported the results of our molecular-dynamics simulations on core-excitation effects during the early stages of high-energy clusters of light atoms (Al) colliding with a high-Z metal surface (Au(100)). In these simulations a simple critical distance model (Re = 0.44 A) was used for L-shell core excitation in Al. The threshold for core-excitation was found to be near 0.4 ke V /atom for pure Al clusters, and significantly lower (~0.11 keV/Al-atom) for mixed Al-Au clusters. Core-excitation was found to be most probable during the early, compressional phase of the cluster impacts, and the probability for a core excited atom being ejected from the cluster-target system was found to be quite high (~40%). Using realistic lifetimes for the core-excited states in the solid, it was estimated that the rate of atomiclike Auger emission from core-excited atoms decaying in the vacuum would be quite high (>0.1 per incident cluster).

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