Rotationally inelastic collisions between a diatomic molecule in a/sup 2/Pi electronic state and a structureless target
We present the full close-coupling formulation of the collision between a diatomic molecule in a /sup 2/Pi state in the Hund's case (a) limit and a structureless target. Due to the possibility of transitions between spin-orbit and/or ..lambda..-doubling states the scattering displays an additional degree of complexity not seen in rotationally inelastic collisions of /sup 1/..sigma../sup +/ molecules. The well-known coupled states and infinite-order-sudden (IOS) approximation techniques can be applied in a straightforward manner. The factorization and scaling relations between the various cross sections, which are valid in the energy sudden limit, are explored. For transitions within either spin-orbit manifold (..cap omega.. = 1/2, ..cap omega.. = 3/2), these scaling relations allow both matrices of cross sections, for parity conserving the parity violating transitions, to be expressed in terms of the cross sections for parity conserving transitions out of the ..cap omega.. = 1/2, J = 1/2 level. Under conditions in which either a Born or sudden formulation of the collision dynamics is appropriate, we show that at large values of the total angular momentum, transitions which conserve the parity index of the molecular wave functions will be strongly favored, a propensity rule which has been seen in previous experimental studies of rotational relaxation in /sup 2/Pi molecules. A scaling relation is also derived for the cross sections for transitions between the two spin-orbit manifolds.
- Research Organization:
- Department of Chemistry, University of Maryland, College Park, Maryland 20742
- OSTI ID:
- 5197973
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 76:12; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
INELASTIC SCATTERING
MOLECULE COLLISIONS
ROTATIONAL STATES
SCATTERING
SUDDEN APPROXIMATION