DESCRIPTION OF HIGH-n STATE POPULATION IN ELECTRON TRANSFER COLLISIONS

The atomic-orbital expansion method is employed in calculations of electron transfer into a range of projectile n states, n0≤n≤n0+4, in H++H, He2++H, C6++H and O8+H collisions at energies 1-80 keV/amu, where n0 indicates the respective dominant transfer channel for each system (n0=1, 2, 4 and 5). It is shown that at low energies, E≤20 keV/amu, some "ladder climbing" mechanism is important for the population of higher-n states, n>n0, such that full-scale close-coupling calculations are required at these energies. It is only at higher energies that some couplings can be dropped for facilitating the calculations.