State-to-state differential cross sections for rotationally inelastic scattering of Na/sub 2/ by He

Journal Article · Thu May 01 04:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5481381

Bergmann, K; Hefter, U; Witt, J

State-to-state differential cross sections for rotational transitions of Na/sub 2/ in collisions with He are measured in the electronic and vibrational ground state at thermal collision energies using a new laser technique. Single rotational levels j/sub i/ are labelled by modulation of their population via laser optical pumping using a dye laser. The modulation of the fluorescence induced by an Ar/sup +/ laser tuned to the level j/sub f/=28 is proportional to the cross section for collisional transfer j/sub i/..-->..j/sub f/ and is detected at the scattering angle theta. A single optical fiber and a fiber bundle provide a flexible connection between the detector and the laser and photomultiplier, respectively. Transitions as large as ..delta..j=20 are observed. At small angles elastic scattering is dominant, but rotationally inelastic processes become increasingly important at larger scattering angles. Rotational rainbow structure causing a steep onset of the cross section with the scattering angle theta (at fixed ..delta..j) or a sharp cutoff with ..delta..j (at fixed theta) is found. Preliminary results on rotational energy transfer in v=1 indicates that vibrational motion of the molecule favors larger rotational quantum jumps. semiclassical picture for the scattering of a hard ellipsoid gives a

• Research Organization: Fachbereich Physik der Universitaet Kaiserslautern, Postfach 3049, 6750 Kaiserslautern, West Germany
• OSTI ID: 5481381
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:9; 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
EXCITED STATES
FLUIDS
HELIUM
METALS
MOLECULE COLLISIONS
NONMETALS
RARE GASES
ROTATIONAL STATES
SODIUM