High resolution FTIR spectrum of CH2D37Cl: ν4 and ν8 fundamental bands

The high-resolution Fourier transform infrared spectrum of CH2D37Cl has been analyzed in the region of the v4 and v8 bands from 1170 to 1370 cm-1. The upper states of these fundamentals, separated by 0.6 cm-1, interact with each other by a-type as well as b-type Coriolis resonance, and a strong asymmetric distribution of the intensity of the rotational structure in each band is observed. The spectral analysis resulted in the assignment of 2774 and 1611 rovibrational transitions for v4 and v8 bands, respectively, which have been simultaneously fitted using Watson’s A-reduction Hamiltonian in the Ir representation and the relevant perturbation operators. A set of spectroscopic constants for the two fundamentals as well as seven coupling terms have been determined. From spectral simulations, the dipole moment ratio |Δμ_a/Δμ_b| of v4 has been determined to be 1.3 ± 0.1 while the intensity ratio between v4 and v8 has been estimated to be 5.0 ± 1.0.