Molecular beam determination of alkali ion-rare gas potentials

Scattering cross sections have been measured for K+ and Na+ on He, Ne, Ar, Kr, and Xe over the LAB energy range of 40–1000 eV. The data have been analyzed to give intermolecular potentials for these systems in the range of thermal energies to ∼ 0.2 eV. The He and Ne systems could be fit with a purely repulsive wall. For the heavier rare gases the strong attractive ion-induced-dipole force contributed measurably in our energy range. The potentials are harder than the corresponding neutral alkali systems with well depths roughly ten times as large.