Charge-changing collisions of argon ions on argon gas. One-electron capture

Abstract

Single-electron-capture cross sections have been measured for argon ions with initial charges $2\ensuremath{\le}q\ensuremath{\le}12$ incident on an argon-gas target. The cross sections show little dependence on the incident ion energy in the range $1q\ensuremath{-}10q$ keV. A remarkable oscillating feature is seen for cross sections ${\ensuremath{\sigma}}_{q,q\ensuremath{-}1}$ when $q\ensuremath{\ge}7$. Particularly, ${\ensuremath{\sigma}}_{8,7}$ is smaller than ${\ensuremath{\sigma}}_{7,6}$ and ${\ensuremath{\sigma}}_{9,8}$, the ${\mathrm{Ar}}^{8+}$ electronic structure being Ne-like. Variation of the cross section is shown as function of the initial charge at constant energy.