Thermal diffusion factors for the binary noble gas mixtures

Thermal diffusion factors for the ten binary mixtures of the noble gases have been measured as a function of composition and temperature in a 20-tube trennschaukel. The compositions ranged from approximately 10 to 90 mole% of the lighter component while the average temperature of measurements for equimolar mixtures ranged from approximately 200 to 800 K. The present data, combined with results by previous workers, were correlated to obtain the ’’best’’ representation for the temperature dependences of each system using a large number of correlating functions. Theoretical thermal diffusion factors for four intermolecular potential schemes were calculated and compared to the resulting correlations. In order to avoid the possible uncertainty of the combining rules for potential parameters, those potentials employed were required to have a complete set of parameters for the ten mixtures and the pure species with the mixture parameters derived from one or more physical properties of the gas mixture. The Dymond–Alder potential with mixture parameters obtained from second virial coefficients proved the most satisfactory.