Centrifugal Distortion in Asymmetric Molecules. II. HDS

A perturbation method for relating the theory of centrifugal distortion in asymmetric top molecules to observed microwave Q branch, $a$ or $c$ type transitions, is presented. The formula for the distortion correction is expressed in terms of the total angular momentum, $J$, the symmetry axis momentum of the nearest symmetric top, $K$, and five distortion constants. The formula yields a satisfactory fit to the observed spectrum of HDS ($\kappa \simeq -0.5\mathrm{}$). The electric dipole moment is determined as 1.02±0.02 debye. The inertia defect and distortion constants are calculated. The effective structure for the HDS molecule so determined is in agreement with infrared determinations.