Dissociative and non-dissociative single-electron capture by CO 2+2 and OCS 2+ from rare-gas atoms

Abstract

Relative abudances of fragment ions and stable M +(CO + 2 and OCS + ions formed in electron-capture collisions with rare-gas targets have been determined by mass-analysed ion kinetic energy spectroscopy in an attempt to determine M + state-occupancy distributions and their variation with rare-gas target. Spectra at 6 or 10 keV collision energy were obtained by use of a “ Z-discrimination avoidance” technique in which a summation of spectra at various off-axis displacements was performed. Distinct trends in fragment-ion relative abundance with target-gas ionization energy were found. By associating each type of fragment ion with a range of excited vibro-electronic states of M +, and with state analysis of the stable M + ions, the relative populations of the various M + states were determined approximately for the reactions of M 2+ with each target gas. The results indicate that the states predominantly occupied in charge-transfer reactions are those which can be reached through curve crossings in the 2–8 Å interparticle separation region.