Effect of Similarity of Particles on Gas Kinetic Quantities with Application to Nuclear Spins

Abstract

In this paper the effect of similarity of particles on gas kinetic quantities (coefficient of viscosity, thermal conductivity, and diffusion) is studied. The symmetrization of the wave function is complicated by the presence of all degrees of freedom which though dynamically unimportant distinguish the particles from each other (orientation of the angular momentum of rotation, electronic and nuclear spins). The theory is applied in detail to the determination of the coefficient of viscosity and thermal conductivity of the ortho- and para-modifications of hydrogen. Marked differences are predicted depending upon the relative concentration of the ortho-para forms. Evaluation of so far uninterpreted measurements of thermal conductivity coefficients lead to good agreement with the theoretically predicted values. It is furthermore found that in the determination of the coefficient of diffusion no symmetrization of the wave functions has to enter. The theory allows in certain favorable cases a determination of nuclear spins of isotopes from viscosity observations, the method being independent of a possibly present magnetic moment. As an experimentally promising example the case of neon is calculated in detail.