Flow birefringence in gaseous mixtures

In an earlier paper, an alignment of the rotational angular momenta of gas molecules produced by a gradient in the stream velocity has been shown to cause a measurable birefringence in the gas. The present paper reports an extension of these measurements to mixtures, specifically N2 and HD with He, Ne and Ar. The concentration dependence found in these experiments can be well interpreted in terms of a kinetic theory, based on the Waldmann-Snider equation, employing data obtained from other experiments, such as the Senftleben-Beenakker effect and depolarized Rayleigh scattering.