Rotational rainbow oscillations in He--Na/sub 2/ collisions: Comparison between coupled states and infinite order sudden approximations

Journal Article · Sat Dec 01 04:00:00 EST 1979 · J. Chem. Phys.; (United States)

OSTI ID:5938801

Schinke, R; McGuire, P

Differential and integral cross sections for the rotational excitation of Na/sub 2/ in collisions with He at 0.1 eV are calculated in the coupled states and the rotationally sudden approximation. The final rotational state distribution at fixed scattering angle exhibits an interference structure similar to the usual rainbow pattern in potential scattering, namely, a broad main rainbow maximum for high ..delta..j transitions and ''supernumerary'' oscillations on the bright side of the rotational rainbow for lower ..delta..j transitions. This rainbow effect is explained in the stationary phase limit of the sudden approximation by interferences between''trajectories'' from different atom--molecule orientations. It is shown that the oscillations in the rotational distribution at fixed angle are equivalent to the oscillations vs scattering angle for a single rotational transition as reported by Schinke (Chem. Phys. 34, 65 (1978)). The sudden cross sections are in satisfactory accord with the coupled-states results, when the average rotational state j-bar is choosen to reflect energy conservation.

• Research Organization: Fachbereich Physik, Universitaet Kaiserslautern 675 Kaiserslautern, West Germany
• OSTI ID: 5938801
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DIFFERENTIAL CROSS SECTIONS
DIMERS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
HELIUM
INTEGRAL CROSS SECTIONS
METALS
MOLECULE COLLISIONS
NONMETALS
RARE GASES
ROTATIONAL STATES
SODIUM
SUDDEN APPROXIMATION