Diffusion and interaction potentials for K+ions in the noble gases

The ratio D T /µ between the transverse diffusion coefficient and the mobility has been measured as a function of the electric field to density ratio E / N , for K + ions in all the noble gases at a temperature of 295 K and with an accuracy of 1% or better. In helium, the experimental data are in excellent agreement with theoretical values obtained from a recent ab initio potential. In the other gases, the experimental data have been used to estimate interaction potential parameters, using a modified Tang-Toennies-type potential model with hyperpolarizabilities included and a generalized Born-Mayer-type repulsive term.