ELECTRON-IMPACT IONIZATION OF SMALL ARGON CLUSTERS

The dynamics of cluster ions following electron impact ionization of A r-n, n = 3, 4, have been modelled theoretically and the calculated fra gmentation probabilities compared with recent measurements using scatt ering deflection techniques. The calculations have been conducted usin g a hybrid quantum/classical treatment on a manifold of 3n coupled pot ential energy surfaces of the ions determined by a diatomic-in-molecul es model plus polarization terms. Branching ratios into the different fragmentation channels have been calculated. The results are in good a greement with measured ion abundances. In particular, in the calculati ons Ar-3(+) ions are not found to be produced by electron impact ioniz ation of Ar-3 and Ar-4, in agreement with the experimental findings.