Differential elastic scattering of He* (2/sup 1/S) by Ar, Kr and Xe: Repulsive rainbows and optical potentials

Journal Article · Fri Sep 15 04:00:00 EDT 1978 · J. Chem. Phys.; (United States)

OSTI ID:6733609

Martin, D W; Gregor, R W; Jordan, R M; Siska, P E

Elastic scattering angular distributions of He* (2/sup 1/S) with Ar, Kr, and Xe measured in crossed atomic beams at collision energies from 0.4--2.8 kcal/mole are analyzed using a physically motivated optical potential model. The resulting potentials show some features expected on the basis of the analogous Li--rare gas potentials: monotonically increasing van der Waals well depths epsilon in the sequence Ar, Kr, Xe, and nearly constant well position r/sub m/. However, structure occurs in the repulsive parts of the potentials in the form of a local slope maximum (force minimum) at low positive potential energy, as suggested by other studies. The potential energy at the slope maximum decreases monotonically in the Ar, Kr, Xe sequence, while its position increases monotonically. The slope maximum is manifested in the angular distributions through the appearance of rainbow scattering peaks for Ar and Kr at angles well removed from those at which attractive rainbows are expected, with both repulsive and attractive rainbows evident in the same distribution. The resonance widths are constrained to be simple exponentials. Table I contains all potential parameters derived. Reasonably good agreement is obtained between measured total ionization cross sections and quenching rate constants and those calculated from the optical potentials.

• Research Organization: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
• OSTI ID: 6733609
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 69:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
ARGON
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
ATOMIC BEAMS
BEAMS
COLLISIONS
CRYOGENIC FLUIDS
DISTRIBUTION
ELASTIC SCATTERING
ELEMENTS
FLUIDS
HELIUM
KRYPTON
NONMETALS
RARE GASES
SCATTERING
XENON