Dissociative ionization of OCS induced by highly charged ion impact

Dissociation of OCSq+ (q = 3-7) produced by 18-keV/uNe(8+) ion impact has been investigated using recoil ion momentum spectroscopy. Ten complete three-body Coulomb fragmentation channels were analyzed. Scattered projectile charge state (Ne7+ or Ne6+) differentiated branching ratios and the kinetic-energy release (KER) distributions were analyzed for different fragmentation channels. Through Dalitz plots, Newton diagrams, and native frames, we have studied the concerted and sequential fragmentation mechanisms for channels leading to O+ + C+ + S+, O+ + C+ + S2+, O2+ + C+ + S+, and O+ + C+ + S3+. For concerted dissociation mechanisms, the molecular bending fragmentation dominates in these channels. For sequential dissociation mechanisms, the KER distribution for the dissociation of intermediate ions CO2+/CS2+ were determined and the rotation of the intermediate molecular ion CO2+ before the second step dissociation was discussed. Thereby the relative branching ratios of events coming from sequential versus concerted mechanism were also estimated.

Automated summary

Through ion impact experiments and momentum spectroscopy, we investigated the dissociation processes of OCSq+ ions and analyzed the branching ratios and kinetic-energy release for different dissociation mechanisms. The results showed distinct differences in the impact of concerted and sequential dissociation mechanisms in various fragmentation channels.