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, K_a ≤ 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.