High resolution FTIR study of the ν4, ν5, ν6, and ν9 fundamental bands of CHD2Cl

This work presents the first high-resolution Fourier transform infrared (FTIR) spectroscopic study of CHD2Cl in the 600 – 1200 cm-1 spectral region. The ν4, ν5, and ν6 fundamentals of both CHD235Cl and CHD237Cl isotopologues were measured and analyzed. A ro-vibrational analysis of 6615 and 2915 assigned transitions for the ³⁵Cl and ³⁷Cl species, respectively, performed using Watson’s A-reduced Hamiltonian in the Ir representation, led to the accurate determination of the spectroscopic parameters of the corresponding excited vibrational states up to quartic centrifugal distortion terms as well as of the several Coriolis interactions perturbing these states. The analysis of their couplings with the v9 = 1 “dark state” yielded reliable values of its vibrational energy and rotational constants. Furthermore, an estimate of the intensity ratio between a- and c-type components in the ν4 and ν5 bands has been determined experimentally.