A PAIR-POTENTIAL MODEL FOR THE STRUCTURES AND VAN DER WAALS VIBRATIONAL FREQUENCIES OF GLYOXAL$\cdot Ar_{n}$ COMPLEXES.
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Date
1989
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Ohio State University
Abstract
A naive pair potential model is used to calculate the intermolecular potential energy surface between glyoxal and argon. The glyoxal molecule is assumed to be composed of fragments (2 H and 2 CO) and the interaction potential is a sum of the individual pair wise potentials .$Ar\cdot H$ and $Ar\cdot CO$, which has been determined by previous molecular beam scattering $experiments.^{1}$ The overall success of this model calculation in comparison with the experimental observations is surprisingly good: (1) The model accurately calculates the two isomeric structures of the glyoxal$\cdot$Ar complex, and the structure of the glyoxal$\cdot Ar_{2}$ complex; (2) The calculated binding energies are consistent with the experimentally observed spectral shifts; (3) The model can account for the experimentally observed large structural change that occurs upon electronic excitation of glyoxal in one of the glyoxal$\cdot$Ar complex structures. A normal mode analysis of the van der Waals vibrational frequencies base on the model potential will also be discussed and compared to experimental results.
Description
$^{1}$ J.P. Toennies, W. Welz, and G. Wolf, J. Chem. Phys. 71, 614 (1979); K. Mirsky, Chem. Phys. 46, 445 (1980).
Author Institution: Department of Chemistry, University of Pennsylvania
Author Institution: Department of Chemistry, University of Pennsylvania