Orientation effects in thermal collisions between ''circular''--Rydberg-state atoms and ground-state helium

Journal Article · Sat Jun 01 04:00:00 EDT 1985 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.31.3593· OSTI ID:5548116

de Prunele, E

A general formulation for thermal collisions between a Rydberg-state atom and a ground-state rare-gas atom is developed within the framework of the impulse approximation. This formulation allows calculation of cross sections for state-to-state transitions for an arbitrary initial orientation between the Rydberg-state atom and the relative velocity of the two partners of the collision. It also allows a direct computation of these cross sections averaged over all orientations, a situation corresponding to a cell experiment. In this formulation, the differential cross sections with respect to the modulus of the momentum transfer are obtained analytically in terms of rotation matrix elements. Numerical applications are made for the case of a sodium atom in a ''circular'' Rydberg state (Vertical Barn,l,m>, with l = m = n-1) colliding with helium. The collisional processes are found to be highly anisotropic. In particular, a selection rule may appear, or disappear, depending upon the initial orientation. The extension to the case where an external electric field is present is also discussed, with special emphasis on symmetry properties.

• Research Organization: Service de Physique des Atomes et des Surfaces, Institut de Recherche Fondamentale, Commissariat a l'Energie Atomique, Centre d'Etudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex, France
• OSTI ID: 5548116
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 31:6; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METALS
ANISOTROPY
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
GASES
HELIUM
IMPULSE APPROXIMATION
LINEAR MOMENTUM
METALS
NONMETALS
NUMERICAL SOLUTION
ORIENTATION
RARE GASES
RYDBERG STATES
SODIUM
SPACE DEPENDENCE