High-resolution Fourier transform infrared spectrum of the ν12 fundamental band of ethylene (C2H4)

Abstract

The infrared spectrum of the ν12 fundamental band of ethylene (C2H4) has been measured with an unapodized resolution of 0.004 cm-1 in the frequency range of 1380-1500 cm-1 using the Fourier transform technique. By assigning and fitting a total of 1387 infrared transitions using a Watson's A-reduced Hamiltonian in the I′ representation, rovibrational constants for the upper state (ν12 = 1) up to five quartic and three sextic centrifugal distortions terms were derived. They represent the most accurate constants for the band so far. The rms deviation of the fit was 0.00033 cm-1. The A-type ν12 band with a band center at 1442.44299±0.00003 cm-1 was found to be relatively free from local frequency perturbations. The inertial defect Δ12 was found to be 0.24201±0.00002 u angstrom2.