State selected removal of vibrationally excited NH/sub 2/(X /sup 2/B/sub 1/(0,. nu. /sub 2/,0)) radicals
The influence of vibrational excitation on the decay rate of NH/sub 2/ radicals in the presence of selected substrates has been studied using the laser-induced fluorescence (LIF) technique. The NH/sub 2/ radicals were generated by infrared multiple photon dissociation (IRMPD) of selected precursors (N/sub 2/H/sub 4/, CH/sub 3/NH/sub 2/), and the state selected NH/sub 2/(v/sup double-prime//sub 2/ = 0,1) decay was observed by means of the sensitive LIF measurement of (NH/sub 2/). The reactions studied were of the type: NH/sub 2/(v)/sub 2/ = 0,1)+R..-->..products, with R = NO, CH/sub 3/NH/sub 2/, N/sub 2/H/sub 4/. The reaction rates were determined under pseudo-first-order conditions, and were found to be strongly dependent on the vibrational state of the NH/sub 2/ radical, e.g., k/sub NO/(v/sup double-prime//sub 2/ = 0) = 1.4 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/ and k/sub NO/(v)/sub 2/ = 1) = 3.2 x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/. This influence of vibrational excitation on the total decay rates is discussed and compared with previously reported data on thermal excitation. In thermal studies of these same chemical reactions, a negative temperature coefficient was found for the reaction rate constants. The contribution of diffusion and of vibrational relaxation processes is also considered, as well as the relative importance of the two-body vs the three-body collision reaction channels: NH/sub 2/+NH/sub 2/..-->..NH/sub 3/+NH and NH/sub 2/+NH/sub 2/+M..-->..N/sub 2/H3$+M for M = O/sub 2/, N/sub 2/, and Ar.
- Research Organization:
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
- OSTI ID:
- 7024682
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 80:12; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
FLUORESCENCE
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
LUMINESCENCE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
RADICALS
REACTION KINETICS
VIBRATIONAL STATES