The mass dependence of the charge transfer cross section in ion-atom scattering

Discusses the explicit mass dependence of the charge transfer cross section for ion-atom scattering within the impact parameter approximation. For the He 2+ -H collision case the procedure of only scaling the projectile 3 He 2+ kinetic energy to facilitate comparison with a calculation based on a 4 He 2+ projectile without incorporating any other dependence on the mass is questioned. As an illustration of this point, it is shown explicitly in a two-state (1s,2s) calculation that for the H + -H and D + -H collisions at an impact velocity of 0.9 (au) the usual scaling procedure is not valid.