Approximate cross sections for charge transfer between ground-state atomic hydrogen and completely stripped ions of C, N, O, Ne, Si, and Ar have been obtained in the velocity range 6 × ${10}^6$ - 7 × ${10}^7$ cm/sec. In these collisions, electron capture occurs predominantly into high-lying orbitals of the product heavy ion. The calculations are made using the Landau-Zener theory modified for application to a multistate system. The peak cross sections are found to increase by about a factor of 5 in going from ${\mathrm{C}}^{+6\mathrm{}}$ (≃ 21 ${\mathrm{\AA }}^2$) to ${\mathrm{Ar}}^{+18\mathrm{}}$ (≃ 110 ${\mathrm{\AA }}^2$) and the cross-section curves tend to "flatten out" for the heavier ions where three or four crossings contribute to the charge exchange. At the higher energies, the cross sections become roughly equal to 1.4 × ${10}^{-16\mathrm{}}$${\mathrm{Z}}^{3/2}$ ${\mathrm{cm}}^2$.

• Received 29 September 1975

DOI:https://doi.org/10.1103/PhysRevA.13.1312