Effects of excitation and orbital alignment on electron transfer in Na⁺-Na collisions

The effects of excitation and orbital alignment on the electron transfer process in Na⁺-Na(3s, 3p) collisions are investigated experimentally and theoretically over a wide range of impact energies. Experimentally, the Na(3p) integral alignment parameter and the ratios between the integral transfer cross sections for Na(3pΣ, Π) targets to that for a Na(3s) target have been determined using an optically prepared target. The results are in good agreement with earlier data at lower energies of Campbell et al. Theoretically, the integral cross section results of our 26-state two-centre atomic orbital close-coupling calculations are in good agreement with all experimental data, including the absolute electron transfer cross section measurements of Daley and Perel. These processes are now well understood over more than three orders of magnitude for the impact energy range.