The mobilities of ions in their parent gases

The available experimental data on the mobilities at low field strengths of ions in their parent gases are analyzed on the basis of a simple theoretical description. It is shown that the maxima observed in recent measurements of charge-transfer cross-sections are difficult to reconcile with measured mobilities of atomic ions in atomic gases, and that it is not necessary to invoke charge transfer to explain the observed mobilities of diatomic and polyatomic molecular ions in atomic gases; however, charge transfer is probably operative in cases of diatomic ions in diatomic gases. Finally, a semi-empirical method is used to predict the mobilities over a wide range of temperature and the charge-transfer cross-sections over a wide range of impact energies of the ions of atomic hydrogen and deuterium, the inert gases, mercury and atomic oxygen, and an estimate is given of the mobility of N+2 ions in N2