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Title Intermolecular potential of anisotropic systems: LiF--Ar and LiF--Kr
Creator/Author Reed, K.A. ; Wharton, L.
Publication Date1977 Apr 15
OSTI IdentifierOSTI ID: 7118160
Other Number(s)CODEN: JCPSA
Resource TypeJournal Article
Resource RelationJ. Chem. Phys. ; Vol/Issue: 66:8
Research OrgJames Franck Institute and Departments of Physics and Chemistry, University of Chicago, Chicago, Illinois 60637
Subject640304 -- Atomic, Molecular & Chemical Physics-- Collision Phenomena; ;ARGON-- ATOM-MOLECULE COLLISIONS;KRYPTON-- ATOM-MOLECULE COLLISIONS;LITHIUM FLUORIDES-- ATOM-MOLECULE COLLISIONS; DIFFERENTIAL CROSS SECTIONS;INTERMOLECULAR FORCES
Related SubjectALKALI METAL COMPOUNDS;ATOM COLLISIONS;COLLISIONS;CROSS SECTIONS;ELEMENTS;FLUORIDES;FLUORINE COMPOUNDS;HALIDES;HALOGEN COMPOUNDS;LITHIUM COMPOUNDS;LITHIUM HALIDES;MOLECULE COLLISIONS;NONMETALS;RARE GASES
Description/Abstract High resolution differential cross sections for LiF scattering from Ar and Kr were measured in the thermal velocity range with varying LiF rotational temperature.^A very narrow velocity distribution in the LiF beam, which reduced the equivalent temperature of the experiment to typically below 1 K, made it possible to resolve the high frequency oscillations of the differential cross section.^Rainbow oscillations were identified and measured.^Effects of experimental convolution were discussed and treated.^Average potential well depths and radii were determined.^It was inferred from the breadth of the primary rainbows that the potential well is not pathological in possessing extremely deep or shallow depths (epsilon) for certain orientations: standard deviation of epsilon is about 50%.^The persistency of the high frequency oscillations with angle is evidence of a quite spherical locus of r/sub m/, although the locus is not necessarily concentric with the center of mass.^The high frequency oscillations and in part the rainbow oscillations are damped by rotational transitions.^The differential cross section is largely independent of the rotational state distribution.^Calculations using an optical model for the scattering and assumed angular dependent potentials permitted a quantitative test of a long range potential model and also permitted a fit of an empirical angular dependent model at the radius of the onset of these transitions.^The quantitative test indicated that neglected repulsive terms are important in the theory.^The fitted empirical model was consistent with the measured dispersion in epsilon.^The radius at which rotational transitions become significant has been determined and lies outside r/sub m/, but inside the radius probed by total scattering cross section measurements.^The potential well parameter r/sub m/=3.8 A, epsilon=4.1 x 10/sup -14/ erg and r/sub m/=3.7 A, epsilon=5.3 x 10/sup -14/ erg were obtained for LiF--Ar and LiF--Kr, respectively.
Country of PublicationUnited States
LanguageEnglish
FormatPages: 3399-3413
System Entry Date2001 May 13

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