Infrared laser spectrum of cis-CHCl = CHF near 1060 cm(-1): rovibrational analysis of the perturbed nu(6) fundamental and determination of the constants of the dark vibrational state nu(9)+nu(10)

Cis-1-chloro-2-fluoroethylene has been synthesized, and the gas-phase infra red spectrum has been investigated in the nu(6) band region around 1060 cm( -1), at Doppler-limited resolution, using a tunable diode laser spectromete r. 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 less than or equal to 8 4, K-a less than or equal to 19) for the nu(6) band of the Cl-35 species, w hose origin is at 1062.224 cm(-1). Different excited state perturbations oc cur throughout the band, caused by the first-order b-type Coriolis resonanc e with the v(9) + nu(10) vibrational state. Using Watson's A-reduction Hami ltonian in the I-r representation, a set of spectroscopic constants for bot h the upper states nu(6) and nu(9) + nu(10) has been obtained. Parameters f or the perturber were determined from the interaction effects near the obse rved crossings in the nu(6) band, using a dyad model including first-order b-type Coriolis interaction.