Charge-transfer and impact-ionization cross sections for fully and partially stripped positive ions colliding with atomic hydrogen

Abstract

Classical trajectory calculations have been used to predict the charge-transfer and impact-ionization cross sections for collisions of ${A}^{+q}$+H in the velocity range of (2-7) \ifmmode\times\else\texttimes\fi{} ${10}^{8}$ cm/sec. The calculations employ a three-dimensional Monte Carlo approach that uses a classical description of the H atom and the Coulomb forces among all particles to obtain the cross sections. The positive ions studied include fully stripped ${A}^{+q}$, with $q=1\ensuremath{-}8, 10, 14, 18, 26, \mathrm{and} 36$, and partially stripped ${\mathrm{B}}^{+q}$, ${\mathrm{C}}^{+q}$, ${\mathrm{N}}^{+q}$, and ${\mathrm{O}}^{+q}$, with $q\ensuremath{\ge}3$. The total electron-loss cross sections (sum of charge exchange and impact ionization) vary only slightly with velocity for the higher charge states and reach a value of 2 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}14}$ ${\mathrm{cm}}^{2}$ for ${\mathrm{Kr}}^{+36}$ + H collisions. The importance of impact ionization relative to charge transfer is found to decrease with increasing $q$ in the velocity range studied. Transition probabilities versus impact parameters are presented for the ${\mathrm{H}}^{+}$ + H and ${\mathrm{Ar}}^{+18}$ + H reactions. The calculations are in reasonable agreement with experimentally measured cross sections for the ${\mathrm{H}}^{+}$, ${\mathrm{C}}^{+q}$, ${\mathrm{N}}^{+q}$, and ${\mathrm{O}}^{q+}$+H systems.