TRANSVERSE DIFFUSION MEASUREMENTS AND MONTE-CARLO SIMULATION STUDIES OF RB+ IONS IN KR AND XE

The ratio of the transverse diffusion coefficient to the mobility (D-T /K) for Rb+ ions drifting in Kr and Xe gases at about 303 K has been m easured at electric field to neutral gas density ratio (E/N) values ra nging from 5 to 500 Td. Calculations of the reduced mobility (K-0) and the ratios of the longitudinal and transverse diffusion coefficients to mobility (D-L/K and D-T/K, respectively) for both Rb+-Kr and Rb+-Xe systems were made using a Monte Carlo simulation (MCS) technique and the interaction potential of Koutselos, Mason, and Viehland [J. Chem. Phys. 93, 7125 (1990)]. Furthermore, D-L/K and D-T/K values were deriv ed from K-0 values obtained from the present MCS calculations and from experimental results reported in the literature, using the generalize d Einstein relations which are based on the three-temperature theory. For the Rb+-Kr system, the experimental values of D-T/K were found to be 2%-4% higher than those from MCS calculations for E/N values above 120 Td. For the Rb+-Xe system, the experimental D-T/K values were simi larly higher than the MCS values in the range 90-220 Td. Given that th e standard error of the experimental measurements of D-T/K is estimate d to be better than 3% and that of the MCS calculations is better than 2.5%, the agreement between the present experimental D-T/K data and t hose from MCS calculations can be considered to be fairly good. The in teraction potential of Koutselos, Mason, and Viehland therefore appear s to represent well the actual potential for both Rb+-Kr and Rb+-Xe sy stems. (C) 1995 American Institute of Physics.