Heat-flow birefringence in gaseous O2

Under the influence of second-order gradients in the temperature, an anisotropy in the rotational angular momenta in a gas can be set up, giving rise to a birefringence. Preliminary measurements on this effect, called heat-flow birefringence, are reported. An interpretation of the results is given based on a kinetic theory for rarefied gases, combined with data obtained from other experiments such as the Senftleben-Beenakker effect and the depolarized Rayleigh scattering.