A study of K+–He and K+–Kr atomic interaction potentials based on transverse diffusion measurements

The ratio of the transverse diffusion coefficient to the mobility, DT/K, has been measured for K+ ions drifting in helium and krypton in the presence of a uniform electric field. Results at 298 K are reported at E/N values ranging from 10 to 220 Td for K+–He and 5 to 420 Td for K+–Kr. Values of DT/K for these two systems were also calculated with a Monte Carlo simulation method which used a number of proposed potentials as input. The accuracy of these potentials has been evaluated by comparing the results to the experimentally determined values. For K+–He none of the available potentials seems to be completely accurate, but for K+ –krypton the potential of Koutselos, Mason, and Viehland appears to be a very good representation of the actual potential. Within the ranges studied, the estimated accuracy of the experimental measurements is ±2.5% and the accuracies for the Monte Carlo calculations are ±1% for K+–He and ±0.5% for K+–Kr.