Re-analysis of the high resolution FTIR spectrum of C2H2D2-cis in the region of 1280-1400 cm−1

- Re-analysis of the v12 band (three times more transitions were assigned, than in the preceding studies).
- Transitions belonging to the 2v10 band are assigned for the first time.
- Resonance interactions in the C2H2D2-cis ethylene.
- Improvement of the ground state parameters of C2H2D2-cis ethylene.

The high-resolution infrared spectrum of C2H2D2-cis ethylene was analyzed in the region of 1280-1400 cm−1, where the strong ν12 band is located. More than 2000 transitions (about three times more than it was made in the preceding studies) were assigned with the maximum values of the upper quantum numbers Jmax.=45 and Kamax.=19 (Jmax.=31 and Kamax.=13 in the preceding studies). For the first time, 22 transitions belonging to the 2ν10 weak band were assigned. For description of the assigned transitions (upper ro-vibrational energy levels), the Hamiltonian model was used which takes into account resonance interactions between the vibrational state (v12=1) and three other closely located states: (v10=2), (v8=v10=1), and (v3=1). A set of 43 spectroscopic parameters obtained from a weighted least square fit reproduces the initial experimental data (817 upper energy values and more than 2000 transitions) with the drms=2.2×10−4cm−1 which is close to experimental uncertainties and considerably better than in prior studies. Ground state rotational and centrifugal distortion parameters were improved on the basis of the IR experimental data of the present study and microwave data from the earlier literature.