Impact parameter treatment of H+-H collisions

A method has recently been introduced by Bates and McDonough (1972) which reduces very much the labour associated with the impact parameter treatment of inelastic ion-atom collisions. This method is used to carry out extensive computations on H + -H(1s) inelastic collisions. It is found that the Born probability of excitation or ionization occurring in a head-on collision is greater than unity if the impact energy lies between 2.5 keV and 50 keV; and that even at 100 keV this probability is greater than 0.2 for impact parameters slightly less than 2 au. Certain general features of the results are qualitatively as would be expected from classical considerations.