Measurement of the Diffusion Coefficient of Oriented Na Atoms in Different Buffer Gases

We report the measurements of the diffusion coefficients of Na in different buffer gases obtained through the study of the optical activity of Na vapour oriented by laser light. The reliability of this method is analysed in the different physical situations to which the different buffer gases give rise. The accuracy of the method, in all cases in which extremely short relaxation processes are absent, is confirmed either by the comparison among the diffusion coefficient values here measured and those present in the literature obtained with different techniques, or by the analysis of the polarization distribution in steady conditions, which results to be in good agreement with the theoretical forecasts.