Termolecular Ion-Atom Association.

Termolecular ion-atom association Rg^ {+} + Rg + M longrightarrow Rg_sp{2}{+} + M is studied over the continuous range of low to high neutral gas density for the rare gases (Rg = He, Ne, Ar, Kr and Xe). The density dependence of the two-body rate coefficient suggests a linear relationship into the tens of atmospheres. Detailed theoretical treatments are provided for the binary rate coefficient and fraction of angular momentum transitions important in the quasi-equilibrium statistical theory. New theoretical developments greatly simplify previously encountered computational complexities. Rates are calculated via the One-Way Continuum to Bound State and Exact treatments for the hard sphere, polarization and charge transfer mechanisms, the results of which are in excellent agreement with experiment.