Ethylene-1-13C (13C12CH4): First analysis of the ν2, ν3 and 2ν10 bands and re-analysis of the ν12 band and of the ground vibrational state

•Ro-vibrational spectra of 12C13CH4.•Resonance interactions in the 12C13CH4 molecule.•Determination of spectroscopic parameters.

High-resolution FTIR ro-vibrational spectra of the 13C12CH4 molecule in the region of 600-1700 cm−1, where the bands ν3, ν12 and ν2 are located, were recorded and analyzed with the Hamiltonian model. This model takes resonance interactions between these three bands as well as strong interactions with six neighboring bands, ν10, ν8, ν7, ν4, ν6, and 2ν10 into account. More than 3800 ro-vibrational transitions belonging to the bands ν3, ν12, ν2 and 2ν10 were assigned (for the first time for the ν2, ν3 and 2ν10 bands) with the maximum values of quantum numbers Jmax./Kamax. equal to 22/8, 52/18, 30/11 and 27/12, respectively. On this basis, a set of 62 vibrational, rotational, centrifugal distortion and resonance interaction parameters was obtained from the weighted fit. These parameters reproduce 1562 initial “experimental” ro-vibrational energy levels obtained from unblended lines with the rms error drms=2.6×10−4cm−1. Furthermore, ground state parameters of the 13C12CH4 molecule were improved.