Subshell electron capture in collisions of fully stripped ions with He andH2at intermediate energies

Classical phase-space models of the hydrogen molecule and helium are utilized to study shell and subshell electron-capture processes in collisions of fully stripped ions on charge states from 1 to 15 with ${\mathrm{H}}_2$ and He at intermediate impact energies (20–200 keV/amu). Autoionization after double electron capture is approximated and is found to be an important channel for high projectile charges. The resulting (n,l) distributions for proton impact of He and ${\mathrm{H}}_2$ as well as total capture cross sections are found to be in very good agreement with experimental data. l distributions for high projectile charges are also analyzed for n levels for which autoionization is negligible. It is found that electrons are captured preferentially to large l values.