Analysis of the coriolis interaction of the ν12 band with 2ν10 of cis-d2-ethylene by high-resolution Fourier transform infrared spectroscopy

The Fourier transform infrared spectrum of the ν12 band of cis-d2-ethylene (cis-C2H2D2) has been recorded with an unapodized resolution of 0.0024 cm−1 in the frequency range of 1280–1400 cm−1. This band was found to be mutually coupled by Coriolis interaction with the unobserved 2ν10 band situated approximately 10 cm−1 below ν12. By fitting a total of 771 infrared transitions of ν12 with a standard deviation of 0.00075 cm−1 using the Watsonʹs Hamiltonian with the inclusion of a c-type Coriolis resonance term, a set of accurate rovibrational constants for V12=1 state was derived. The ν12 band is A type with a band centre at 1341.1512±0.0001 cm−1. Accurate rovibrational constants for the V10=2 state were also derived.