Diffusion and thermal diffusion in some dilute binary gaseous systems between 195 and 400 K: Tests of several asymmetric potentials using the infinite order sudden approximation

Limiting binary diffusion coefficients, D012, for mixtures of He with Ar, O2, N2, CO2 and SF6 and of Ar with N2 and O2, determined by the two-bulb method, are reported for the temperature range 195–400 K. The apparatus, calibrated with absolute data obtained at 300 K with a Loschmidt cell, greatly extends the temperature range covered in this Laboratory, previously limited to 275–325 K. Thermal diffusion factors, αT, have been measured for the systems He-Ar at 350 K with He-O2, He-CO2 and Ar-O2 at 255.3 K. These results together with others previously reported have been used to test several asymmetric potential functions recently published in the literature.