Energy redistribution in low energy collisions between I/sub 2/* and He
The process of collision-induced energy transfer between an excited I/sub 2/ molecule and a He atom has been studied in a supersonic free jet expansion. The relative rates of vibrational relaxation as well as the extent of the rotational energy transfer were measured by observing the dispersed fluorescence spectrum of the I/sub 2/* molecule. Results show that the vibrational relaxation cross section is much larger in a supersonic free jet than in a hot static gas, and this indicates that the low energy colllisions prevalent in the jet are much more effective than are high energy collisions. Mechanisms for energy transfer and relaxation enhancement in cold collisions are discussed. A comparison is made between the collision-induced energy redistribution in I/sub 2/* and the energy distribution in the photodissociation of the van der Waals molecule I/sub 2/He. Results show that in a collision more extensive rotational energy transfer occurs, and that the branching ratio of the ..delta..v'=-2 to the ..delta..v'=-1 vibrational relaxation processes is much larger than in the decomposition of the I/sub 2/He* van der Waals complex.
- Research Organization:
- The James Franck Institute and The Department of Chemistry, The University of Chicago, Chicago, Illinois 60637
- OSTI ID:
- 5555262
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:5; 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
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HALOGENS
HELIUM
IODINE
MOLECULE COLLISIONS
NONMETALS
RARE GASES
RELAXATION
VIBRATIONAL STATES