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Title: Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/

Abstract

Differential scattering cross sections are measured for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, and SF/sub 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/sub 4/, NH/sub 3/, H/sub 2/O 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/sub 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.

Authors:
; ;
Publication Date:
Research Org.:
Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125
OSTI Identifier:
6197588
Resource Type:
Journal Article
Journal Name:
J. Chem. Phys.; (United States)
Additional Journal Information:
Journal Volume: 70:3
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; AMMONIA; ATOM-MOLECULE COLLISIONS; HELIUM; METHANE; SULFUR FLUORIDES; WATER VAPOR; INTERMOLECULAR FORCES; MOLECULAR BEAMS; VAN DER WAALS FORCES; ALKANES; ATOM COLLISIONS; BEAMS; COLLISIONS; CRYOGENIC FLUIDS; ELEMENTS; FLUIDS; FLUORIDES; FLUORINE COMPOUNDS; GASES; HALIDES; HALOGEN COMPOUNDS; HYDRIDES; HYDROCARBONS; HYDROGEN COMPOUNDS; MOLECULE COLLISIONS; NITROGEN COMPOUNDS; NITROGEN HYDRIDES; NONMETALS; ORGANIC COMPOUNDS; RARE GASES; SULFUR COMPOUNDS; VAPORS; 640304* - Atomic, Molecular & Chemical Physics- Collision Phenomena

Citation Formats

Slankas, J.T., Keil, M., and Kuppermann, A. Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/. United States: N. p., 1979. Web.
Slankas, J.T., Keil, M., & Kuppermann, A. Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/. United States.
Slankas, J.T., Keil, M., and Kuppermann, A. Thu . "Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/". United States.
@article{osti_6197588,
title = {Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/},
author = {Slankas, J.T. and Keil, M. and Kuppermann, A.},
abstractNote = {Differential scattering cross sections are measured for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, and SF/sub 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/sub 4/, NH/sub 3/, H/sub 2/O 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/sub 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.},
doi = {},
journal = {J. Chem. Phys.; (United States)},
number = ,
volume = 70:3,
place = {United States},
year = {1979},
month = {2}
}