Quasi-Lorentzian diffusion of D 2 and HD in noble gases

Abstract

Relative diffusion coefficients have been measured for the quasi-Lorentzian gas mixtures of D 2 and HD with the noble gases He, Ne, Ar, Kr and Xe, in the temperature range from 237 to 420 K. The accuracy of the data is one or two per mil. Satisfactory agreement has been obtained with experimental data reported in the literature. The behaviour of the temperature dependence of the diffusion coefficients for all mixtures studied, expressed in terms of the function [2-(∂ 1n D 12/∂ 1n T) p ] agrees quite well with theoretical expectations. Comparison of semi-empirical thermal diffusion factors, calculated from the experimental values of this function and the diffusion cross sections, with direct measurements shows a remarkable agreement. The reliability of the theoretical expressions for the higher order corrections of the diffusion coefficients used is confirmed by the excellent agreement between theory and experiment with respect to the concentration dependence of the diffusion coefficient.