Fermi resonance and Coriolis coupling between upsilon(5) and 2 upsilon(6) in CH2 (CIF)-C-35

The rotational spectra of CH2 (ClF)-Cl-35 in the vibrational excited states v(5) = 1 and v(6) = 2 have been observed in the frequency region 8-250 GHz. From infrared data these states are predicted to be close in energy (2v(6) - v(5) = 10 cm(-1)) and both a Fermi resonance and a third-rank Coriolis resonance between them have been considered in the analysis of the rotational spectra. The Cl-35 quadrupole coupling constants have been also determined from the analysis of the hyperfine structure for both vibrational states. (C) 1996 Academic Press, Inc.