Diode laser spectrum and rovibrational analysis of the ν6 band of vinyl fluoride

Abstract

The vibration–rotation spectrum of CH2=CHF has been investigated in the ν6 band region around 1305 cm−1 at Doppler limited resolution using a tunable diode laser spectrometer. The measurements have been performed at low temperature (240 K) to decrease hot band interferences. This fundamental of symmetry species A′ gives rise to an a/b hybrid band, which was mainly composed of a-type transitions. Both J and K structures have been resolved in the QQK(J) subbranches and the rovibrational analysis in the P, Q, and R branches has led to the identification of more than 1000 lines with J ≤ 43 and Ka ≤ 14. The ν6 band is affected by first-order b-type and second-order a-type Coriolis resonances with the ν9 + νn combination, and the perturbation effect has been found stronger for the [Formula: see text]level. About 870 transitions free of major resonance contributions were fitted using Watson's A-reduction Hamiltonian in the Ir representation, and a set of effective rotational and quartic centrifugal distortion constants was determined for the ν6 = 1 state of CH2=CHF.