The Coriolis interaction between the nu(9) and nu(7) fundamental bands of methylene fluoride

The infrared spectrum of the nu and v,bands of methylene fluoride-d(2) (CD2 F2) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 940-1030 cm(-1) using the Fourier transform technique. A weak b-type Coriolis interaction term was found to couple these two vibra tional states with band centers about 42 cm(-1) apart. By fitting a total o f 1031 infrared transitions of both nu(7) and nu(9) with a standard deviati on of 0.0011 cm(-1) using a Watson's A-reduced Hamiltonian in the I' repres entation with the inclusion of a b-type Coriolis resonance term, two sets o f rovibrational constants for nu(7) = 1 and nu(9) = 1 states up to sextic o rder were derived. The nu(7) band is C type, while the nu(9) band is A type with band centers at 961.8958 +/- 0.0005 and 1003.7421 +/- 0.0001 cm(-1), respectively. (C) 2000 Academic Press.