Thermal Diffusion Factor and Quantum Collision Integrals for theH2sngbnd;4HeSystem: The Effect of Inelastic Collisions

摘要

We have extended our measurements of the composition dependence of the thermal diffusion factor of the hydrogenhyphen;helium system to lower temperatures in search of the inelastic (rotational) collision effect reported by Ghoshet al.and Mathur and Watson. We measured agr;Tas a function of composition in a seventube trennschaukel at an average temperature of 82deg;K and failed to find any maxima or minima greater than our average experimental scatter of approximatelyplusmn; 10percnt;. We have also determined the temperature dependence of the thermal diffusion factor for an equimolar mixture from 30 to 550deg;K which is characterized by a broad maximum at approximately 125deg;K. A sharp decrease in agr;Twas observed on the low temperature side of the maximum while a gradual, almost linear decrease was obtained on the high temperature side. We have calculated quantum mechanical transport collision integrals for hydrogenhyphen;helium assuming an (exphyphen;6) spherical interaction potential and have used them to evaluate agr;T3, the third order Chapmanhyphen;Enskog approximation to the thermal diffusion factor. The theoretical calculations are in excellent agreement with the experimental determinations.