Slankas, John T. and Keil, Mark and Kuppermann, Aron (1979) Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+ CH_4, NH_3, H_2O, SF_6. Journal of Chemical Physics, 70 (3). pp. 1482-1491. ISSN 0021-9606 http://resolver.caltech.edu/CaltechAUTHORS:20120727-084321227
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Differential scattering cross sections are measured for He+CH_4, NH_3, H_2O, and SF_6, using the crossed molecular beams technique. These data, which are sensitive to the van der Waals attractive minima and adjacent regions of the intermolecular potential, are interpreted in terms of central‐field models. No evidence is found for quenching of the observed diffraction oscillations. The interactions of the isoelectronic hydrides CH_4, NH_3, H_2O with He are found to have decreasing van der Waals radii in this sequence, and their attractive wells all have similar depths. However, the He+SF_6 attractive well is found to be anomalously deep, and provides a counter example to the supposition that only the polarizability of the least polarizable of the interacting partners (atoms or molecules) correlates with the van der Waals well depth. Simple combination rules for predicting unlike‐pair potential parameters from the corresponding like‐pair ones are tested and found inadequate.
|Additional Information:||© 1979 American Institute of Physics. Received 6 June 1978. Online Publication Date: 28 July 2008. This work was supported in part by a Contract (EY-76-S-03-767) from the Department of Energy. Report Code: CALT-767P4-175. Work performed in partial fulfillment of the requirements for the Ph.D. degree in Chemistry at the California Institute of Technology. Contribution No. 5798. We wish to thank Ambassador College for generous use of its computing facilities.|
|Subject Keywords:||MOLECULAR BEAMS, HELIUM, METHANE, AMMONIA, WATER VAPOR, SULFUR FLUORIDES, INTERMOLECULAR FORCES, VAN DER WAALS FORCES, ATOM−MOLECULE COLLISIONS|
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|Classification Code:||PACS: 34.20.-b, 34.50.Lf|
|Official Citation:||Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH4, NH3, H2O, SF6 John T. Slankas, Mark Keil, and Aron Kuppermann J. Chem. Phys. 70, 1482 (1979); http://dx.doi.org/10.1063/1.437587|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||30 Jul 2012 15:46|
|Last Modified:||26 Dec 2012 15:45|
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