First high resolution ro-vibrational analysis of C2HD3 in the region of the ν12 band

The high-resolution infrared spectra of C2HD3 ethylene was analyzed for the first time in the region of 1230-1340 cm−1, where the strong ν12 band is located. The 1748 transitions with the maximum values of the upper quantum numbers Jmax.=43 and Kamax.=14 were assigned to the ν12 band. The 14 transitions have been assigned to the 2ν10 band whose appearance is caused by the strong resonance interaction with the ν12 one. For description of the assigned transitions (upper ro-vibrational energy levels), the effective Hamiltonian was used which takes resonance interactions between the vibrational state (v12=1) and three other closely located states, (v10=2),(v7=v10=1) and (v4=v10=1) into account. A set of 70 spectroscopic parameters obtained from a weighted least square fit reproduces the initial experimental data (593 upper energy values, 1762 transitions) with the drms= 1.3 ×10−3 cm−1. Finally, the strengths of 106 ro-vibrational lines of the ν12 band were roughly estimated.