Multiple ionization and complete fragmentation of OCS by impact with highly charged ions Ar4+ and Ar8+ at 15 keV q−1

Abstract

We have used time- and position-sensitive detection in a coincidence arrangement to study the multiple ionization of OCS in collisions with Ar4+ and Ar8+ at 15 keV q−1 followed by complete breakup of the molecule OCS—Oa++ Cb+ + Sc+. We have compared our results with theoretical values derived by simulating the breakup, from ground state distributions of bond lengths and bond angle assuming a point-like ion and purely Coulombic potential. This comparison shows that in general the experimental distributions of energy release are broader and peak at lower energy than calculated. Better agreement between measurement and calculation is however found with increasing the final charge state. Furthermore, the amount of induced bending is considerably less for the high charge states. However, even where total energy release is close to Coulombic (6+) individual fragment ion energy distributions differ from the expected values because of the degree of bending. Using Newton and Dalitz plots, we are able to identify the extent of concerted and stepwise processes. Our results indicate a higher degree of asymmetric bond processes at a low charge state (3+) where small amounts (<7%) of the stepwise processes are also measurable.