High-resolution FTIR spectra of CH₂ = CClF in the 930-1050 cm⁻¹ region

Abstract

The gas-phase infrared spectra of natural CH₂ = CClF have been measured in the v ₆ and 2v ₁₂ band regions (930–1050 cm⁻¹) by high-resolution Fourier transform spectroscopy at room temperature. 1-Chloro-1-fluoroethylene is a planar asymmetric rotor (κ = −0.54) belonging to the symmetry point group C_s and the vibrations investigated of symmetry species A′ give rise to a/b-hybrid bands with contributions of comparable intensity from both the components.

The rovibrational analysis of the fine structure led to the identification of 1894 (J ⩽ 73, K_a ⩽ 20) and 718 (J ⩽ 53, K_a ⩽ 8) transitions for the v ₆ and 2v ₁₂ bands of the ³⁵Cl isotopic species, respectively. Using the Watson's A-reduction Hamiltonian in the I^r representation a set of accurate spectroscopic parameters for both the excited states u ₆ = 1 and u12 = 2 of ³⁵Cl has been obtained for the first time. Transitions of ³⁷Cl isotopomer could also be assigned in the Q branch region of the 2v ₁₂ overtone; the determined band origin shift of 0.782 cm⁻¹ towards the lower wavenumbers led to describing the v ₁₂ fundamental as a vibration mainly involving the CFCl bending motion.