Molecular dynamics simulation of the cluster-impact-induced molecular desorption process

Molecular dynamics computer simulation is used to investigate the effects o f cluster surface interactions and their use to desorb molecules from a sur face. Of interest here is the interaction of fullerenes with a graphite sur face and in particular cluster impact desorption of adsorbed molecules from the graphite surface. It has been shown recently how impacts from fullerenes on graphite cause an acoustic wave to propagate across the surface from the impact site. In the work presented here it is shown that this wave can be used to desorb intac t molecules that are weakly bonded by Van der Waals forces to the surface. The ultimate objective is to desorb molecules the size of genes. Using C-60 , a wave can be created that is strong enough to desorb 15 benzene molecule s without breaking either the surface of the graphite or any of the benzene molecules. It is unlikely that this will be strong enough to desorb a high -mass gene. By increasing the initial energy of the C-60, we desorb a large r number of molecules but at the expense of breaking the surface, losing th e coherence of the acoustic wave and breaking many of the benzene molecules . However, if the size of the impacting molecule is increased to that of a 300-particle 'onion'-type structure, it is possible to increase greatly the power of the acoustic wave, thereby desorbing many more benzene molecules from the surface without causing any damage to the surface, the fullerene o r to the benzene molecules themselves. Copyright (C) 2001 John Wiley & Sons , Ltd.