High-resolution FTIR analysis of the 2ν6 overtone of cis-CHFCHF and Fermi resonance study with the ν2 fundamental

The 2ν6 overtone band (1659.43 cm-1) of cis-CHFCHF has been recorded with an unapodized resolution of 0.004 cm-1, using a multipass cell and a Fourier transform infrared spectrometer. More than 2300 transitions have been assigned and fitted to the Watson’s A-reduced Hamiltonian in the Ir representation yielding accurate spectroscopic parameters up to three sextic coefficients. The vibrational resonance of 2ν6 with the ν2 fundamental was also considered and, as a result, the Fermi coupling term, the unperturbed vibrational levels and molecular parameters have been calculated. Additionally, information on the infrared inactive ν6 vibration have been derived.