Low-energy electron capture byCl7+from D using merged beams

Abstract

Measurements of the absolute total cross section for single-electron capture in collisions of ${\mathrm{Cl}}^{7+}$ with ground-state atomic deuterium are reported in the energy range 4.6--428 eV/amu. These measurements represent the highest charge state yet reported using the Oak Ridge National Laboratory ion-atom merged-beams apparatus. The electron-capture cross section for ${\mathrm{Cl}}^{7+}$ is observed to decrease at lower energies, in contradiction to what is expected from a popular simple model and speculation from previous measurements for highly charged $(7+)$ ions with multielectron cores. The observed low-energy behavior is interpreted using coupled-channel molecular-orbital hidden-crossing calculations for ${\mathrm{N}}^{7+}+\mathrm{D}.$