High-resolution Fourier transform infrared spectrum of the nu(12) fundamental band of ethylene (C2H4)

The infrared spectrum of the nu(12) fundamental band of ethylene (C2H4) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequen cy range of 1380-1500 cm(-1) using the Fourier transform technique. By assi gning and fitting a total of 1387 infrared transitions using a Watson's A-r educed Hamiltonian in the I-r representation, rovibrational constants for t he upper state (nu(12) = 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 nu(12) band with a band center at 1442.44299 +/- 0.00003 cm(-1) was found to be relatively free from local frequency perturbations. The inerti al defect Delta(12) was found to be 0.24201 +/- 0.00002 u Angstrom(2). (C) 2000 Academic Press.