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Scattering of thermal He beams by crossed atomic and molecular beams. II. The He-Ar van der Waals potential

Keil, Mark and Slankas, John T. and Kuppermann, Aron (1979) Scattering of thermal He beams by crossed atomic and molecular beams. II. The He-Ar van der Waals potential. Journal of Chemical Physics, 70 (1). pp. 482-503. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:20120726-080235906

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Abstract

Differential cross sections for He–Ar scattering at room temperature have been measured. The experimental consistency of these measurements with others performed in different laboratories is demonstrated. Despite this consistency, the present van der Waals well depth of 1.78 meV, accurate to 10%, is smaller by 20% to 50% than the experimental values obtained previously. These discrepancies are caused by differences between the assumed mathematical forms or between the assumed dispersion coefficients of the potentials used in the present paper and those of previous studies. Independent investigations have shown that the previous assumptions are inappropriate for providing accurate potentials from fits to experimental differential cross section data for He–Ar. We use two forms free of this inadequacy in the present analysis: a modified version of the Simons–Parr–Finlan–Dunham (SPFD) potential, and a double Morse–van der Waals (M^2SV) type of parameterization. The resulting He–Ar potentials are shown to be equal to with experimental error, throughout the range of interatomic distances to which the scattering data are sensitive. The SPFD or M^2SV potentials are combined with a repulsive potential previously determined exclusively from fits to gas phase bulk properties. The resulting potentials, valid over the extended range of interatomic distances r≳2.4 Å, are able to reproduce all these bulk properties quite well, without adversely affecting the quality of the fits to the DCS


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1063/1.437213DOIUNSPECIFIED
http://jcp.aip.org/resource/1/jcpsa6/v70/i1/p482_s1PublisherUNSPECIFIED
Additional Information:© 1979 American Institute of Physics. Received 17 April 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-767P4-167.Work performed in partial fulfillment of the requirements for the Ph. D. degree in Chemistry at the California Institute of Technology. Contribution No. 5762. We wish to thank Messrs. W. W. Schuelke, A. W. Stark, and I. Moskovitz of the Instrument and Electronics Shops of the Division of Chemistry and Chemical Engineering at Caltech for their talented technical support of the apparatus. We also wish to thank Ambassador College for generous use of its computing facilities.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)EY-76-S-03-767
Subject Keywords: VAN DER WAALS FORCES, HELIUM, ARGON, ATOMIC BEAMS, ATOM−ATOM COLLISIONS, DIFFERENTIAL CROSS SECTIONS
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Report CodeCALT-767P4-167
Caltech Arthur Amos Noyes Laboratory of Chemical Physics5762
Classification Code:PACS: 34.50.Fa, 34.20.-b
Record Number:CaltechAUTHORS:20120726-080235906
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120726-080235906
Official Citation: Scattering of thermal He beams by crossed atomic and molecular beams. II. The He–Ar van der Waals potential Mark Keilb), John T. Slankas, and Aron Kuppermann J. Chem. Phys. 70, 482 (1979); http://dx.doi.org/10.1063/1.437213
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:32734
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:30 Jul 2012 16:24
Last Modified:26 Dec 2012 15:44

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