Charge Exchange between Gaseous Ions and Atoms

A calculation of symmetric resonant charge exchange cross sections has been made for a selection of atoms in the velocity range where the impact parameter method is applicable. Cross sections for other atoms can be estimated by interpolating in terms of their ionization potentials. The results are in fair agreement with experiment. A similar calculation has been attempted for asymmetric nonresonant charge exchange processes. The approximations used are more restrictive in this calculation, the calculations being only semiquantitative in nature. The cross section of an asymmetric charge exchange process is determined in terms of the ΔE of the reaction and the ``average'' ionization potential of the two atoms. The results are qualitatively in agreement with experiment. A very brief discussion of approaches for extrapolating data to lower velocities, where the rectilinear orbit impact parameter method is not applicable, is given.