Traveling-molecular-orbital-expansion studies of electron capture in collisions of fully stripped ions (Z=6–9) with H andH2

The traveling-molecular-orbital-expansion description has been employed to investigate electron capture in collisions of fully stripped ions (Z=6–9) with H and ${\mathrm{H}}_2$ in the energy regime from 0.14 to 9 keV/amu. The pseudopotential method was used to represent the ${\mathrm{H}}_2$ ${\mathrm{}}^{+}$ core which enables us to treat the ${\mathrm{H}}_2$ molecule as an atom having an ionization potential for ${\mathrm{H}}_2$→${\mathrm{H}}_2$ ${\mathrm{}}^{+}$. Features of the adiabatic potentials and corresponding radial coupling matrix elements at the ‘‘reaction window’’ as well as the quantitative results of relatively small-scale close-coupling calculations provide a rationale for the interpretation of a recent measurement for these systems by Meyer et al. [Phys. Rev. A 32, 3310 (1985)]. For collisions of ${\mathrm{O}}^{8+}$ with H, an extended molecular-orbital-expansion approach has been employed (i) to seek an understanding of the discrepancy evident in two recent independent large-scale calculations for n=6 partial cross sections, and (ii) to obtain a quantitative test for the mechanism suggested in this paper.