Temperature dependence of vibrational energy transfer in NH/sub 3/ and H/sub 2/ /sup 18/O
The V..-->..T, R relaxation rate for NH/sub 3/ (..nu../sub 2/) has been studied from 198 to 398 /sup 0/K by the method of laser-excited vibrational fluorescence. The self-deactivation rate constant decreases from 4.9 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ sec/sup -1/ at 198 /sup 0/K to 2.7 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ sec/sup -1/ at 398 /sup 0/K. The rate constants for deactivation by He, Ar, N/sub 2/, and O/sub 2/ are much smaller and show a weak temperature dependence in the opposite direction. For H/sub 2/ /sup 18/O the vibrational relaxation rates of the coupled ..nu../sub 1/, ..nu../sub 3/ stretching level manifold and of the 2..nu../sub 2/ bending level have been studied from 250 to 400 /sup 0/K. The ..nu../sub 1/, ..nu../sub 3/ self-deactivation rate goes from 3.5 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ sec/sup -1/ at 250 /sup 0/K to 2.0 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ sec/sup -1/ at 400 /sup 0/K. For 2..nu../sub 2/ it goes from 1.2 x 10/sup -10/ to 7.8 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ sec/sup -1/. The temperature depencence of the deactivation of both levels by He and Ar is much weaker and the rates are several hundred times slower. CO/sub 2/ deactivates ..nu../sub 1/, ..nu../sub 3/ about 50 times faster than He or Ar at 293 /sup 0/K.
- Research Organization:
- Department of Chemistry, University of California, Berkeley, California 94720
- OSTI ID:
- 5484626
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:4; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AMMONIA
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
FLUIDS
GASES
HELIUM
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
NITROGEN
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
OXYGEN
RARE GASES
RELAXATION
TEMPERATURE DEPENDENCE
VAPORS
VIBRATIONAL STATES
WATER VAPOR