MICROWAVE ROTATIONAL SPECTRA OF THE $Ar-C_{2}H_{4}$ and $Ne-C_{2}H_{4}$ VAN DER WAALS DIMERS

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 Title: MICROWAVE ROTATIONAL SPECTRA OF THE $Ar-C_{2}H_{4}$ and $Ne-C_{2}H_{4}$ VAN DER WAALS DIMERS Creators: Liu, Yaqian; Jäger, Wolfgang Issue Date: 1999 Publisher: Ohio State University Abstract: Rotational spectra of various isotopomers of the $Ar-C_{2}H_{4}$ and $Ne-C_{2}H_{4}$ van der Waals dimers were measured in the frequency range from 3.5 to 22 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The observed transitions are all of a-type. The observed spectra are consistent with planar, T-shaped equilibrium geometries. Tunneling splittings were observed for all transitions. This is attributed to an internal rotation motion of the ethylene unit within the complex. $Ne-C_{2}H_{4}$ shows a larger tunneling splitting than $Ar-C_{2}H_{4}$, which can be attributed to a lower tunneling barrier in the $Ne-C_{2}H_{4}$ case. Molecular symmetry group analyses using nuclear permutation inversion group theory can explain teh observed intensity variation and the absence of certain transitions. Effective separations beteen the center-of-mass of ethylene and the rare gas atoms were obtained from the ground state rotational constants. ab initio calculations at the MP4 level were carried out on $Ne-C_{2}H_{4}$, and the results were compared with those from the experiments. Description: Author Institution: Department of Chemistry, University of Alberta URI: http://hdl.handle.net/1811/19546 Other Identifiers: 1999-WF-06