High-resolution Fourier transform infrared spectroscopy and analysis of the ν12 fundamental band of ethylene-d4

The Fourier transform infrared (IR) spectrum of the v(12) fundamental band of ethylene-d(4) (C2D4) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 1030-1130 cm(-1). A total of 1340 assigned transitions have been analyzed and fitted using a Watson's A-reduced Hamiltonian in the I-r representation to derive rovibrational constants for the upper state (v(12) = 1) up to five quartic terms with a standard deviation of 0.00042 cm(-1) They represent the most accurate constants for the band thus far. The ground state rovibrational constants were also further improved by a fit of combination-differences from the IR measurements. The relatively unperturbed band was found to be basically A-type with a band centre at 1076.98492 +/- 0.00003 cm(-1). (C) 1999 Elsevier Science B.V. All rights reserved.