Laser infrared spectroscopy of vinyl fluoride in the 1280–1400 cm−1 region

Abstract

The infrared spectra of CH2=CHF have been investigated in the ν5 and ν6 band regions between 1280 and 1400 cm−1, at a resolution of about 0.002 cm−1, using a tunable diode laser spectrometer. These vibrations of symmetry species A′ give rise to a/b-hybrid bands with different contributions from both the components. Spectral analysis resulted in the identification of 1565 (J≤46, K a ≤11) and 1651 (J≤48, K a ≤15) transitions of the ν5 and ν6 fundamentals, respectively. Both bands are perturbed by the nearby states ν8 + ν9 and ν9 + ν11 through different Coriolis resonances and an anharmonic interaction. Using Watson's A-reduction Hamiltonian in the Ir representation and perturbation operators almost all the transitions have been fitted simultaneously to a model including six resonances within the tetrad ν5/ν6/ν8 + ν9/ν9 + ν11. A set of spectroscopic constants for the ν5 and ν6 bands, as well as parameters for the dark states ν8 + ν9 and ν9 + ν11 and coupling constants, have been determined. From spectral simulations the dipole moment ratio |Δμ a /Δμ b | was estimated to be 0.6 ± 0.1 and 2.0±0.3 for the ν5 and ν6 bands, respectively.