High resolution infrared synchrotron study of CH2D81Br: ground state constants and analysis of the ν5, ν6 and ν9 fundamentals

The high resolution infrared absorption spectrum of CH2D81Br has been recorded by Fourier transform spectroscopy in the range 550–1075 cm−1, with an unapodized resolution of 0.0025 cm−1, employing a synchrotron radiation source. This spectral region is characterized by the ν6 (593.872 cm−1), ν5 (768.710 cm−1) and ν9 (930.295 cm−1) fundamental bands. The ground state constants up to sextic centrifugal distortion terms have been obtained for the first time by ground-state combination differences from the three bands and subsequently employed for the evaluation of the excited state parameters. Watson's A-reduced Hamiltonian in the Ir representation has been used in the calculations. The ν 6 = 1 level is essentially free from perturbation whereas the ν 5 = 1 and ν 9 = 1 states are mutually interacting through a-type Coriolis coupling. Accurate spectroscopic parameters of the three excited vibrational states and a high-order coupling constant which takes into account the interaction between ν5 and ν9 have been...