MICROWAVE SPECTROSCOPIC INVESTIGATION OF THIONYL CHLORIDE, SOCL2 - HYPERFINE CONSTANTS AND HARMONIC FORCE-FIELD

The rotational spectrum of the most abundant isotopomer of thionyl chl oride, S-32 O-16 Cl-35(2), has been recorded in the frequency range 7. 8-24.7 GHz using a pulsed molecular-beam microwave spectrometer. 262 l ines of 27 rotational transitions (b- and c-type) have been used to de termine rotational and quartic centrifugal distortion constants and th e complete Cl-35 nuclear quadrupole coupling tenser, as well as spin-r otation coupling constants. Whereas the diagonal quadrupole coupling c onstants in the inertial axis system agree with those from previous mi crowave studies, disagreement is observed for the principal values chi (zz) (-63.8 MHz) and eta (-0.0143). However, the value of chi(zz) is i n good agreement with those derived from solid-state NQR measurements. The centrifugal distortion constants together with vibrational wavenu mbers and amplitudes have been used to refine the harmonic force field . The principal quadrupole coupling constants and the force constants are compared with those of related molecules, and the latter have been used to propose a reassignment of two vibrational bands of the relate d molecule, SO2Cl2.