RG13		10min4:52

HOLGER S. P. MÜLLER, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; PAUL HELMINGER, Department of Physics, University of South Alabama, Mobile, AL 36688; SIDNEY H. YOUNG, Department of Chemistry, University of South Alabama, Mobile, AL 36688.

The rotational spectrum of ClONO₂ has been (re-) investigated in the millimeter and submillimeter regions in the ground vibrational and first excited torsional states for both ³⁵Cl and ³⁷Cl isotopomers. A large number of a- and b-type R- and Q-branch as well as b-type P-branch transitions have been observed. This has enabled the improvement of the spectroscopic constants and the prediction of lines in the submillimeter region. Accidental near-degeneracies of rotational levels allowed the observation of a J = 2 transition and the precise determination of the off-diagonal quadrupole coupling constant \chi_ab. The quartic distortion constants along with the vibrational wavenumbers and inertial defects have been used to calculate a harmonic force field. The results will be related to the molecular structure determined from an electron diffraction study and to data from related molecules such as Cl₂O.