Modified method of perturbed stationary states. V. Electron-capture cross sections for the reactionO8++H(1s)→O7+(n,l)+H+

Abstract

Electron-capture cross sections are reported for the reaction ${\mathrm{O}}^{8+}+\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}\to {\mathrm{O}}^{7+}\mathrm{}(n,l)+{\mathrm{H}}^{+}$, with $n=4,5,6\mathrm{}$ and $l=0\mathrm{}$ through $n-1\mathrm{}$. The cross section for $n=7\mathrm{}$ is also estimated. The energy range extends from 13 eV/amu to 34 keV/amu. A Landau-Zener formula is given for use at lower energies. The calculations are quite analogous to those carried out for ${\mathrm{C}}^{6+}-\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$ collisions in Phys. Rev. A 25, 1364 (1982), The modified perturbed-stationary-state calculation features the use of a mixed representation of diabatic and adiabatic states and the use of translation factors determined by Euler-Lagrange optimization within the mixed representation of states. One internuclear separation-dependent factor is used for the initial state, which correlates to ${\mathrm{O}}^{8+}+\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$. A second factor is used for all the ${\mathrm{O}}^{7+}$+${\mathrm{H}}^{+}$ correlating states. Riley's semiclassical average approximation is used at low energies and the straight-line impact-parameter method is used at high energies. For the purpose of comparison, some calculations are also carried out by the method of Bates and McCarroll and by that of Piacentini and Salin. The approximation of neglecting $\pi$-$\pi$ and $\Delta$-$\Delta$ couplings is tested. The results are compared with those of other researchers.