Molecular dynamics simulations were performed to study the behavior of cluster SIMS. Two predominant cluster ion beam sources, C-60 and Au-3, were chosen for comparison. An amorphous water ice substrate was bombarded with incident energy of 5 keV. The C-60 cluster was observed to shatter upon impact creating a crater of damage approximately 8 nm deep. Although Au-3 was also found to both break apart and form a damage crater, it continued along its initial trajectory causing damage roughly 10 nm deep into the sample and becoming completely imbedded. It is suggested that this difference in behavior is due to the large mass of Au relative to the substrate water molecule. (c) 2006 Elsevier B.V. All rights reserved.