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

High-resolution infrared spectroscopy of CH281BrF near 8 μm: rovibrational analysis of the ν3 and ν8 fundamentals and resonances with the dark states 2ν5 and ν6 + ν9

“…In the present case, the effects of first-order b-type Coriolis resonance between ν 8 and 4ν 6 (A ) reported for CH 2 79 BrF [18] were not observed.…”

“…The initial parameters for the υ 8 = 1 and υ 6 = υ 9 = 1 states were taken from the ground state. The band origins were derived for ν 8 from [8] and for ν 6 + ν 9 combining the ν 6 and ν 9 band centres from [8] and [13], respectively; the anharmonicity constant x 69 was assumed equal to that of CH 2 79 BrF [8] while the initial value of the Coriolis interaction term ξ c 8,69 was considered equal to that of the 79 Br isotopologue [18]. In the fitting procedure of the ν 8 transitions the same steps used for ν 3 were adopted and the best representation of the interacting dyad was obtained by constraining the sextic centrifugal distortion constants for both vibrational levels and the quartic coefficients for ν 6 + ν 9 to the ground state values.…”