High resolution FTIR spectrum of CH2D79Br: the ground, v5 = 1 and v9 = 1 state constants

The first high-resolution infrared spectrum of CH2D79Br has been investigated in the range 710–1080 cm-1 by Fourier transform infrared spectroscopy employing a synchrotron radiation source at an unapodized resolution of 0.0025 cm-1. This spectral region accounts for the fundamental bands v5 (v0=768.809 cm-1) and v9 (v0=930.354 cm-1), having the structure of hybrid a/b- and c-type bands of near-prolate asymmetric tops, respectively. The rovibrational analysis was performed over a wide range of transitions with quantum numbers J<=72 and Ka<=16. The experimentally determined ground-state constants including four sextic coefficients were obtained for the first time by merging the ground-state combination differences of the two bands. The A-reduced Watson Hamiltonian in the Ir representation was adopted to fit the data. Only weak interaction effects ascribed to a-type Coriolis coupling influenced the Ka=10–14 stacks of the bands. The residuals were adjusted by including one higher-order interaction term in a dyad model.