Thermal Diffusion in Krypton and Argon

The mathematical description of a two-bulb thermal diffusion experiment is extended to the case of multicomponents isotopic mixtures. A self-consistent method of comparing two-bulb data to theoretical predictions is developed and applied to the argon data of Stier. The best fit for the modified Buckingham exp-six, α=14, intermolecular potential model is obtained for a force constant, ε/k=110°K. Measurements of the thermal diffusion factor of krypton versus temperature are presented and compared to the Lennard-Jones (9,5) and (13,7) and the modified Buckingham exp-six, α=14 models, yielding the force constant values, ε/k=169, 395, and 470°K, respectively.