Extension to third-order Coriolis terms of the analysis of ν10, ν7, and ν4 levels of ethylene on the basis of Fourier transform and diode laser spectra

Abstract The ν 7 , ν 10 , and ν 4 levels of ethylene have been studied based on waveguide laser, Fourier transform, and diode laser spectra in the range from 798 to 1091 cm −1 . The absolute calibration of these spectra is better than 0.0002 cm −1 . To deal with so many and so accurate experimental data, we have developed in our analysis programs the Watson Hamiltonian up to the sextic centrifugal distortion coefficients and the interaction Hamiltonian up to the third-order Coriolis resonance terms. The molecular parameters of the vibrational ground state have been significantly improved on the basis of more than 4000 GSCD. In the analysis of ν 7 , ν 10 , and ν 4 levels, we had to introduce the ν 12 level, which contributes to the indirect coupling of ν 7 and ν 4 through strong Coriolis interactions. We obtain a statistical agreement with all experimental data with an estimated standard deviation equal to 0.84. The intrinsic intensity of the ν 10 band has been determined to be 16 500 ± 2500 times lower than the intensity of the ν 7 band.