High-resolution FTIR spectroscopy of HCFC-31 in the 950-1160 cm(-1) region: rovibrational analysis and resonances in the.4,.9 and.5+.6 bands of (CH2ClF)-Cl-35

The FTIR spectrum of CH2ClF (natural isotopic mixture) was investigated in the (4), (9) and (5)+(6) band region between 950 and 1160 cm(-1) at the resolution of 0.004 cm(-1). The (4) and (5)+(6) vibrations of A symmetry give rise to a/b hybrid bands with a predominant a-type component. The (9) vibration of A symmetry, expected with a c-type band contour, shows an intense Coriolis-induced parallel component (K-a = 0, K-c = 0) derived from mixing with the v(4) = 1 vibrational state. The high-resolution spectra of (9) and (5)+(6) have been analyzed for the first time, while the assignments of the (4) band, previously investigated, have been extended to higher J and K-a values in the b-type component. The spectral analysis resulted in the identification of 1508, 809 and 349 transitions for the (4), (9) and (5)+(6) bands of (CH2ClF)-Cl-35, respectively. Besides the strong first-order a- and b-type Coriolis resonances between (4) and (9), the (5)+(6) vibration was found to interact through a c-type Coriolis with the (4) and 3(6). High-order anharmonic resonance (K-a = +/- 2) between (4) and (5)+(6)was also established. All the assigned data were simultaneously fitted using the Watson's A-reduction Hamiltonian in the I-r representation and the relevant perturbation operators. The model employed includes five types of resonances within the tetrad (4)/(9)/(5)+(6)/3(6). set of spectroscopic constants for (4), (9) and (5)+(6) bands as well as parameters for the dark state 3(6) and seven coupling terms have been determined. The simulations performed in different spectral regions satisfactorily reproduce the experimental data.