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.