Ion-atom charge exchange at low energies

The cross section for charge exchange between ions and atoms is calculated for the case when the concept of classical trajectory is inapplicabte for desribing the reiative motion of the particles. In the limiting case of fast collisiops the formula derived is identical to the Rozen-Zener-Demkov formula. An expression for the Massey parameter is obtained which is valid for describing inelastic reactions in low energy collisions. The results are compared with results of a numerical calculation of the cross section for charge exchange between slow protons and hydrogen atoms