Ion–polar neutral momentum transfer collision frequencies: A theoretical approach

A simple statistical theory is proposed which gives quantitative values for ion–polar neutral momentum transfer collision frequencies. The calculated collision frequencies depend on the rotational temperature of the neutrals, the translational temperature of the ions and neutrals, the masses of the ion and neutral, and the ratio of the neutral dipole moment to the square root of the neutral polarizability. Agreement with available experimental collision frequencies is very good. The results are consistent with available experimental rate constants for exothermic proton transfer reactions. The effects of nonorbiting collisions and finite ion–neutral hard sphere radius are examined.