Interchange of Charge between Gaseous Molecules in Resonant and Near-Resonant Processes

Interchange of charge between monatomic and diatomic ions and molecules in gaseous systems is considered theoretically by an ``impact parameter'' method. Formulas for charge transfer cross sections for resonant and near-resonant cases are developed, and comparisons are made between experimental and theoretical results. The validity of the impact parameter method is considered by comparison with the more rigorous method of scattered waves.