Electron capture and excitation in slow H+ + He*(n) collisions

Electron capture and excitation (de-excitation) processes in slow collisions of protons with excited helium, H+ + He*(1s, NL) --> H*(nl) + He+(1s) or --> H+ + He*(1 s, N'L'), are studied by using the close coupling of the states {N, n} = 2, 3, 4 within the approach described in a previous paper. At small collision velocities, 10(6) cm s(-1) < v < 5 x 10(7) cm s(-1), the cross sections for excitation(de-excitation) are very large, due to the importance of two-step transitions. The coupling of the states with different principal quantum numbers significantly increases the cross sections for electron capture at adiabatically small collision velocities.