Analysis of the ν11 band of ethylene-13C2 by high-resolution Fourier transform infrared spectroscopy

The spectrum of the ν11 band of ethylene–13C2 (13C2H4) was recorded with an resolution of 0.006 cm−1 in the 2910–3020 cm−1 region by Fourier transform infrared (FTIR) spectroscopy. Accurate rovibrational constants for the upper state (v11=1) up to sextic centrifugal distortion terms were derived for the first time by fitting 583 transitions using a Watsonʹs A-reduced Hamiltonian in the Ir representation. The rms deviation of the fit was 0.00084 cm−1. The ν11 band was centered at 2969.601695 ± 0.000099 cm−1. The ground state constants were improved by fitting 1052 combination-differences from the present ν11 measurements and those of ν12.