Charge exchange and ionization in ion-atom collisions

The general theory of charge exchange in atom-atom and ion-atom collisions is examined at the various levels of approximation that are made possible by comparing collision energies and typical electron binding energies. The impact parameter approximation and the high energy methods are examined and the corresponding merits of several possible functional expansion methods are discussed. The molecular state expansion is seen both within the impact parameter and the quantum mechanical formulations, while diabatic representations are also analyzed. A few important illustrative examples are reported in the last section