MOLECULAR-DYNAMICS SIMULATION OF XE+ ION COLLISIONS WITH AR29 AND NE29 CLUSTERS

The attachment of Xe+ ions with thermal energies (T = 500 K) to Ar29 a nd Ne29 clusters has been studied using the classical molecular dynami cs (MD) simulation procedure. The dynamics and kinetics of this proces s is different from that of the collisions of neutral rare gas atoms w ith van der Waals clusters because of the long-range ion-induced dipol e electrostatic forces causing the projectile to interact simultaneous ly with all cluster atoms. The fragmentation pattern of (Ar29Xe+) clu ster ions produced by Xe+ ion attachment was compared with that of (Ar 29+) cluster ions produced by direct electron impact ionization and i t was found that the ion attachment is a ''softer'' ionization process than electron impact ionization. This agrees with previous experiment al results. Cross sections estimated from the MD simulations are found to be in good agreement with a modified Langevin-type cross section.