MILLIMETER AND SUBMILLIMETER SPECTROSCOPY OF CHLORINE NITRATE - THE CI QUADRUPOLE TENSOR AND THE HARMONIC FORCE-FIELD

The rotational spectra of (ClONO2)-Cl-35 and (ClONO2)-Cl-37 in their g round and first excited torsional states (v(9) = 1) have been reinvest igated in selected regions between 84 and 441 GHz. An extensive set of spectroscopic constants has been determined, enabeling more accurate predictions of line positions in the submillimeter region. Accidental near-degeneracies of rotational levels cause perturbations of the quad rupole patterns, allow the observation of a Delta J = 2 transition, an d result in the precise determination of chi(ab). The quartic distorti on constants along with the vibrational wavenumbers and inertial defec t differences have been used for a calculation of the harmonic force f ield. The assignments of the vibrational modes in terms of internal co ordinates are discussed. The results are compared with properties of r elated molecules such as Cl2O. (C) 1997 Academic Press.