Resonant charge transfer in collisions between positive ions.

We present a numerical evaluation of the resonant charge-transfer cross sections for ions of various positive charges. In the calculations we introduce trajectory parameters through the expression for the instantaneous velocity of the projectile. Subsequent analysis reveals the existence of a natural scaling law by which cross sections of ion-ion collisions can be generated from the isoelectronic ion-atom charge-exchange cross section. We obtain a set of simple formulas useful for a semiquantitative description of the features of such cross section curves and we discuss the oscillatory structure of the cross sections.