THE ROTATIONAL SPECTRUM OF CBRCLF2 (HALON BCF) .2. THE LOWEST EXCITEDVIBRATIONAL-STATES AND NUCLEAR-QUADRUPOLE COUPLING TENSORS

The analysis of the millimeter-wave rotational spectrum of the well-kn own halon molecule CBrCIF2 was extended to rotational transitions in t he excited vibrational states nu(9) = 1 (307 cm(-1)) and nu(5) = 1 (33 7 cm(-1)). The two states are appreciably coupled by a-and b-axis Cori olis interaction which was treated explicitly and spectroscopic consta nts were determined from measurements at frequencies from 121 to 330 G Hz and J'' from 18 to 111. The present work, together with our previou s study (1996. J. Mel. Spectrosc. 177, 240-250), results in accurate c onstants in the rotational Hamiltonian for the four lowest vibrational states of (CBrClF2)-Br-79-Cl-35 and (CBrClF2)-Br-81-Cl-35. The double nucleus hyperfine structure in low-J transitions of the two Cl-35 iso topomers of CBrClF2, was also measured in the region 3-14 GHz with a s upersonic beam, cavity Fourier transform microwave spectrometer. All c onstants in both the inertial and the principal nuclear quadrupole cou pling tensors have been determined for both Br and Cl nuclei. (C) 1997 Academic Press.