MILLIMETERWAVE SPECTRUM OF ETHYLENE
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Date
2004
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Publisher
Ohio State University
Abstract
The rotational spectra of deuterated isotopomers of ethylene, $H_{2}C=CH_{2}$, have already been $measured^{a}$. The parent species in its ground vibrational state, as far as it is concerned, has no rotational spectrum because it has no permanent dipole moment. However, the vibrational states $\nu_{7} = 1$ and $\nu_{8} = 1$ are close in energy (at 948.77 and $939.86 cm^{-1}$, respectively) and some allowed transitions between these two states lie in the millimeterwave range. The $\nu_{7}$ state is known with an accuracy better than $10^{-6} cm^{-1}$ thanks to $CO_{2}$ laser sideband spectra $^{b}$. The $\nu_{8}$ state has been estimated with an accuracy of the order of $10^{-3} cm^{-1}$ by combining the $\nu_{7} + \nu_{8}$ band with the hot band $\nu_{7} !+ \nu_{8} - \nu_{8}$, both analysed in F.T. spectra (unpublished results). The spectrum has been measured from 180 to 500 GHz and more than 30 transitions have been assigned without ambiguity to ethylene, with a systematic deviation of about -27 MHz from the predictions. A new analysis of the $\nu_{8}$ state has been performed, including the a-type Coriolis interaction with the $\nu_{6}$ state, and a good agreement has been obtained.
Description
$^{a}$E. Hirota, Y. Endo, S. Saito, K. Yoshida, I. Yamaguchi, and K. Machida, J. Mol. Spectrosc. 89 (1981) 223. $^{b}$E. Rusinek, H. Fichoux, M. Khelkhal, F. Herlemont, J. Legrand, and A. Fayt, J. Mol. Spectrosc. 189, 64-73 (1998).
Author Institution: Laboratoire de Physique des Lasers, Atomes et Mol\'{e}cules, UMR CNRS 8523, Universit\'{e} de Lille 1; Molecular Spectroscopy Laboratory, Universit\'{e} Catholique de Louvain
Author Institution: Laboratoire de Physique des Lasers, Atomes et Mol\'{e}cules, UMR CNRS 8523, Universit\'{e} de Lille 1; Molecular Spectroscopy Laboratory, Universit\'{e} Catholique de Louvain