Abstract

Details of the measurement and procedure of analysis of the ${\ensuremath{\nu}}_{\ensuremath{\sigma}}+3{\ensuremath{\nu}}_{\ensuremath{\pi}}$ band of ${\mathrm{H}}_{2}$S are given. An approximate correction for the rotational distortion of the molecule is included. Assignments are made which satisfactorily account for 84 of the 91 measured lines. The remaining 7 lines are considered spurious. The theory for a rigid rotator plus the distortion correction gives a very good approximation to the rotational energy levels of the ${\mathrm{H}}_{2}$S molecule, but many deviations are observed which are definitely larger than the experimental error. The moments of inertia in the normal vibrational state are 2.667, 3.076, 5.845\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}40}$ g ${\mathrm{cm}}^{2}$, the axis of least inertia being perpendicular to the symmetry axis of the molecule. The bond angle is 92\ifmmode^\circ\else\textdegree\fi{} 20\ensuremath{'} and the H---S distance 1.345A.