ORIENTATION DEPENDENCE IN ELECTRON-CAPTURE TO ARBITRARY PROJECTILE N STATES FROM MOLECULAR-HYDROGEN

The dependence on the orientation of the intermolecular axis of cross sections for electron capture from molecular hydrogen by bare ions is calculated in a two-center approximation, which ignores multiple scattering between atomic centers and is compared to experiment. Electron-capture cross sections are calculated as functions of both projectile principal quantum number n and molecular orientation angles. Orientation-averaged cross sections are compared with recent measurements of O8+ + H-2 at E = 8, 10, 12.5, 16, and 20 MeV. Comparisons are also made between our calculations for electron capture into projectile n states by H+ from H-2 and the available calculation for ns states from E = 50 keV to 5 MeV. The orientation-dependence differential in the molecular-orientation angle is studied in dissociative ionization and excitation of the molecular ion following single-electron capture from H-2 using a two-step independent-electron model. The calculated orientation dependence is in qualitative agreement with preliminary experimental observations as a function of the orientation angle done with O8+ ions at E = 10 MeV, where capture to n > 1 state is significant.