Transport properties of He-CO mixtures

Abstract

Classical trajectory calculations for the collision of He with CO have been carried out, with CO treated as a rigid rotor, for two similar potential energy surfaces, one obtained from high level ab initio calculations and the other from a semi-empirical fit to the infrared spectra of He-CO van der Waals dimers. Second-approximation corrections to the kinetic-theory expressions have been employed in order to carry out comparisons with the most accurate and precise diffusion, shear viscosity, thermal conductivity and thermal diffusion data available. Rotational relaxation data are also considered. Both potentials are found to have good predictive power for these transport and relaxation properties, giving on the whole very good agreement with the experimental data. This indicates that the isotropic components of the two potential surfaces are very similar, and that the anisotropies are not significantly different. It is suggested that the measurement of additional relaxation phenomena in He-CO mixtures could allow a clearer distinction to be made between the two potential surfaces.