Using a classical method, cross sections in $A^{q+}+(\mathrm{H},{\mathrm{H}}_2)\hspace{0.5em}(q=1,\dots ,8)$ collisions are obtained for impact energy ranges $9\hspace{0.5em}{\mathrm{keV}\mathrm{}\mathrm{amu}}^{-1}–6.4\hspace{0.5em}{\mathrm{MeV}\mathrm{}\mathrm{amu}}^{-1}$ (ionization), $–600\hspace{0.5em}{\mathrm{KeV}\mathrm{}\mathrm{amu}}^{-1}$ (electron capture). For bare ion impact on H, comparison to experiment and to the results of accurate semiclassical calculations shows that total and partial cross sections, as well as transition probabilities, obtained with the classical trajectory Monte Carlo approach, are more accurate than usually assumed. From the characteristics of the mechanisms, we are led to use our data as estimates for the case of dressed-ion impact at the higher nuclear velocities. We successfully apply a very simple model for ${\mathrm{H}}_2$ targets, in which the relevant quantities are the charge of the projectile and the vertical ionization potential of the molecule. For practical purposes, we give scaling laws to benchmark $({\mathrm{H}}^{+},{\mathrm{He}}^{2+})$ cases, and for ionization we relate them, at higher $v,$ to the behavior of the transition probabilities.

• Received 17 May 1999

DOI:https://doi.org/10.1103/PhysRevA.60.4546