Thermal diffusion factors for equimolar He–Ar from 80 to 640 K and equimolar He–Xe from 140 to 270 K

New experimental measurements of the thermal diffusion factor are presented for the He–Ar and He–Xe system which serve to better define the temperature dependence of αT, particularly at low temperatures. The present results and all previously published data were used to obtain correlation functions accurate to within a few percent. Parameters for a Hartree–Fock dispersion (HFD)-type potential with individually damped dispersion terms were derived allowing accurate theoretical calculations to be made for transport properties, scattering cross sections, and the second virial coefficient.