Simultaneous Determination of Rotational and Translational Temperatures ofOH(Π2)in a Gas Discharge

Abstract

We have made simultaneous determination of the rotational and translational temperatures of $\mathrm{OH}\left({}_{}{}^2{}_{}{}^{}\Pi \right)$ in a water-vapor discharge. These temperatures were determined by measuring the strength and line shape of the absorption lines in the ${}_{}{}^2{}_{}{}^{}\Pi \mathrm{}(v=0\mathrm{})\mathrm{}\to {}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}\mathrm{}(v=0\mathrm{})\mathrm{}$ transitions of OH using a cw tunable laser. It was found that the rotational distribution was thermalized, but the corresponding rotational temperature was much lower than the translational temperature. Possible implications of these results are discussed.