Birefringence in the Boundary Layer of a Rarefied Heat Conducting Gas

In a heat conducting gas of diatomic molecules enclosed between parallel plates, the second rank tensor polarization of the rotational angular momenta can be shown to be nonzero in a boundary layer near the plates, a few mean free paths thick. This phenomenon can be experimentally studied by measuring the birefringence of the boundary layer. Although the predicted effects are very small (An of the order of 10 ), the existence of this effect is clearly demonstrated and qualitative results are obtained for N , CO and HD