High-resolution FTIR spectroscopy of CHD279Br: ro-vibrational analysis of the v4 fundamental and determination of the ground state constants

The first high-resolution infrared spectrum of CHD279Br has been investigated by Fourier transform spectroscopy in the range 940–1100 cm−1 at an unapodised resolution of 0.0025 cm−1. This spectral region is characterised by the v4 (1036.8389 cm−1) fundamental band, corresponding to the CD2 wagging mode. The rotational structure of the a- and c-type components of the hybrid band has been extensively assigned for transitions involving values of J and Ka up to 65 and 15, respectively. The ground state constants up to the quartic centrifugal distortion terms have been obtained for the first time by ground state combination differences from 5251 assigned transitions and subsequently employed for the evaluation of the band origin and the excited state parameters of v4. Watson’s S-reduced Hamiltonian in the Ir representation has been used in the ro-vibrational analysis. The dipole moment ratio |Δμa/Δμc| of the band has been estimated to be 1.3 ± 0.1 from spectral simulations.