Single‐electron capture spectra for Ar 3+ in argon and xenon

High‐resolution translational energy spectra have been obtained for Ar 2+ ions resulting from single‐electron capture by 9 keV Ar 3+ ions in argon and xenon gas targets. Our result for Ar 3+ in argon is broadly in agreement with previous high‐resolution studies, but we have further successfully assigned reaction channels to three peaks which were previously observed but not definitively identified. These channels appear to involve capture of a 3s‐electron from the target argon atom to form Ar + ions in the first excited state Ar + [3s3p 6 2 S]. The capture spectrum for Ar 3+ in xenon displays eleven relatively well defined peaks with exothermic energy changes in the range of 4–12 eV. However, these capture channels are difficult to identify with certainty because they involve capture into closely spaced high excited states of Ar 2+ , and are further complicated by the splitting (1.31 eV) of the ground‐state doublet 2 P target Xe + product ion. There are over one hundred competing channels, comprising three entrance and over forty exit channels, within this range of energy change. Tentative assignments of capture channels have been made, guided by electron‐core configuration and spin‐conservation requirements.