Time dependent thermal lensing measurements of V -- T energy transfer from highly excited NO sub 2
- Department of Atmospheric, Oceanic, University of Michigan, Ann Arbor, Michigan 48109-2143 (USA) Space Sciences, Space Physics Research Laboratory, The University of Michigan, Ann Arbor, Michigan 48109-2143 (USA)
The time dependent thermal lensing technique has been used to measure the vibrational relaxation of NO{sub 2} (initially excited at 21 631 cm{sup {minus}1}) by Ar, Kr, and Xe. The energy transfer analysis was carried out in terms of {l angle}{l angle}{Delta}{ital E}{r angle}{r angle}, the bulk average energy transferred per collision. This quantity was found to have a very strong dependence on vibrational energy, with a marked increase at energies greater than about 10 000 cm{sup {minus}1}, where several electronic excited states ({sup 2}{ital B}{sub 2}, {sup 2}{ital B}{sub 1}, and {sup 2}{ital A}{sub 2}) mix with the ground state ({sup 2}{ital A}{sub 1}). This effect may be due to large amplitude vibrational motions associated with the coupled electronic states. Even at low energies, deactivation is faster than in other triatomic systems, probably because NO{sub 2} is an open shell molecule and electronic curve crossings provide efficient pathways for vibrational deactivation. The {ital V}--{ital T} rate constant for deactivation of NO{sub 2}(010) by argon is estimated to be (5.1{plus minus}1.0){times}10{sup {minus}14} cm{sup 3} s{sup {minus}1}. Results obtained for NO{sup *}{sub 2}--NO{sub 2} collisions gave {l angle}{l angle}{Delta}{ital E}{r angle}{r angle} values in good agreement with literature results from fluorescence quenching experiments, indicating that {ital V}--{ital T} may be more important than {ital V}--{ital V} energy transfer in the quenching process.
- OSTI ID:
- 7002874
- Journal Information:
- Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:8; ISSN JCPSA; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CHALCOGENIDES
COLLISIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
FLUIDS
GASES
KRYPTON
LASER RADIATION
LASER SPECTROSCOPY
MOLECULE COLLISIONS
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
RARE GASES
RELAXATION
SPECTROSCOPY
VIBRATIONAL STATES
XENON