Infrared laser spectrum of cis-CHCI=CHF near 1060cm−1: rovibrational analysis of the perturbed ν6 fundamental and determination of the constants of the dark vibrational state ν9 + ν10

Abstract

Cis-1-chloro-2-fluoroethylene has been synthesized, and the gas-phase infrared spectrum has been investigated in the ν6 band region around 1060 cm−1, at Doppler-limited resolution, using a tunable diode laser spectrometer. This fundamental of symmetry species A′ presents an a/b-hybrid band with contributions from both the components. The rovibrational analysis led to the identification of more than 2000 transitions (J ≤ 84, Ka ≤ 19) for the ν6 band of the 35C1 species, whose origin is at 1062.224cm−1. Different excited state perturbations occur throughout the band, caused by the first-order b-type Coriolis resonance with the ν9 + ν10 vibrational state. Using Watson's A-reduction Hamiltonian in the I r representation, a set of spectroscopic constants for both the upper states ν6 and ν9 + ν10 has been obtained. Parameters for the perturber were determined from the interaction effects near the observed crossings in the ν6 band, using a dyad model including first-order b-type Coriolis interaction.