Thermal diffusion in binary mixtures of linear molecules

Abstract

The composition dependence of the thermal diffusion factors alpha T of the binary gas mixtures NO-CO, N2-C2H2, NO-C2H2 and CO-C2H2 have been studied by the swing separator method. All these systems have the special feature that the gases involved are linear molecules so that interpretation of the data in terms of inelastic theories is feasible. Attempts have been made to interpret the data by using both elastic and inelastic theories of thermal diffusion. The results indicate the influence of inelastic collisions on thermal diffusion in polyatomic gas mixtures. However, the inelastic theories available cannot explain satisfactorily the experimental data. It has been suggested that a more sophisticated theory involving more rigorously defined inelastic cross sections will be necessary for a proper interpretation to be made of the effects of inelastic collisions on thermal diffusion.