EFFECT OF MOLECULAR ANGULAR MOMENTUM ON RELAXATION TIMES AND ENERGY TRANSFER

Author Institution: Department of Chemistry, University of Missouri-RollaThe formal kinetic theory of gases composed of polyatomic molecules was first developed by Wang Chang and Uhlenbeck, and by Monchick, Yun, and Mason. Kagan and Afanas’ev showed that, if the molecules possess angular momentum, the perturbation part of the distribution function should be written in terms of the two independent vector quantities, linear momentum and angular momentum. The angular momentum term accounts for the polarization of the molecules caused by gradients in the gas and is called ``spin polarization”. The purpose of this work is to investigate the effects of spin polarization on relaxation times. Since relaxation times depend only on inelastic collision processes, this transport property provides detailed information about energy transfer. The bulk viscosity, K, for a system including spin polarization is given by \kappa=-{kT}\sum_{rm q}{n}_{q}({d^{1}_{{q}100}}+\frac{1}{3}{d^{2}_{{q}100}} subject to the auxiliary condition \sum_{rm q}{n}_{q}(\frac{3}{2})({d)^{1}_{{q}100}}+\frac{1}{3}{d)^{2}_{{q}100}})-({C}_{qint}/{k})(\frac{3}{2})({d)^{1}_{{q}010}}+\frac{1}{3}{d)^{2}_{{q}010}})=0 The relaxation time, $\tau$, is related to the bulk viscosity by \kappa={kc}_{int}{pt}/{c}^{2}_{v} where p is the pressure. The various $d_{q}$’s are expansion coefficients which are determined from the set of integral equations {R}_{qnpt}\sum_{q^{\prime}}\sum_{npt}\sum_{n^{\prime}p^{\prime}t^{\prime}}\{{d}^{1}_{q^{\prime}n^{\prime}p^{\prime}t^{\prime}}{q}^{npt, n^{\prime}p^{\prime}t^{\prime}}_{qq^{\prime}ab}+{d}^{2}_{q^{\prime}n^{\prime}p^{\prime}t^{\prime}}{q}^{npt, n^{\prime}p^{\prime}t^{\prime}}_{qq^{\prime}cd}\} The evaluation of the $d_{q}$’s in terms of the Q’s will be discussed and formal results for $\tau$ will be presented. Relaxation processes in a single component gas and the relationship to energy transfer as it effects other transport properties will also be considered