High resolution FTIR spectroscopy of CH279BrF: Analysis of the ν8 fundamental band

The infrared spectrum of the 79Br isotopologue of CH2BrF has been recorded by Fourier transform spectroscopy with a resolution of ca. 0.0030 cm−1. The analysis has been performed in the region of the weak ν8 (A″) fundamental band (ν0 = 1226.4275 cm−1). The c-type band shows the typical structure of near prolate asymmetric rotors with asymmetry splitting for low Ka quantum numbers. The v8 = 1 state is moderately perturbed by near combination and overtone levels. The transitions of ν8 and the perturbation-allowed transitions attributed to the interacting bands ν6 + ν9 and 4ν6 have been fitted to the Watson A-reduced Hamiltonian model in the Ir-representation along with the operators accounting for first-order Coriolis coupling between the excited states of these bands. A total of 2037 transitions have been assigned and fitted with a standard deviation about half the accuracy of measurements.