DISSOCIATIVE XENON ION CAPTURE BY NEUTRAL ARGON CLUSTERS

In this paper we describe and discuss a new approach to the production of van der Waals cluster ions. Instead of ionizing pre-existing neutr al clusters by electron impact, Xe+ ions interact with neutral Ar-m cl usters and produce, via a dissociative ion capture process, mixed ArnX e+ ions. This new ionization mode appears to be softer than electron i mpact (i.e. it leads to less fragmentation). Measured cluster ion dist ributions and metastable fragmentation spectra show the anomalous abun dance typical of icosahedral shell and subshell closures, which do not appear when argon clusters are ionized by electron impact. Furthermor e we have used classical molecular dynamics to simulate ionization via this dissociative ion capture process and found that the agreement be tween the simulation and the experiment is very good.