Kinetics of the reaction OH + HO/sub 2/. -->. H/sub 2/O + O/sub 2/ from 254 to 382 K
The discharge-flow resonance fluorescence technique has been used to determine the absolute rate constant for the reaction OH + HO/sub 2/ ..-->.. H/sub 2/O + O/sub 2/ from 254 to 382 K at a total pressure of 1 Torr. Pseudo-first-order conditions were used with HO/sub 2/ in large excess over OH. The rate constant was obtained directly from observed decays of OH and measured concentrations of HO/sub 2/. Since the observed rate constant was found to be very sensitive to small background concentrations of O and H atoms, NO/sub 2/ was used to remove both atoms species from the system. With added NO/sub 2/ the result at 299 K is (1.1 +/- 0.3) x 10/sup -10/ cm/sup 3/ molecule/sup -1/ s/sup -1/ where the error limits are one standard deviation and include an estimate of overall experimental uncertainty. The temperature dependence expressed in Arrhenius form is (4.8 +/- 0.8) x 10/sup -11/ exp((250 +/- 50)/T). The results are independent of the type of reactor surface and the precursor used to produce OH and HO/sub 2/. The present results agree well with earlier measurements near 1-atm total pressure and suggest that this rate constant exhibits little or no pressure dependence between 1 and 1000 Torr.
- Research Organization:
- California Institute of Technology, Pasadena (USA)
- OSTI ID:
- 7005035
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 92:5
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
HYDROPEROXY RADICALS
CHEMICAL REACTIONS
HYDROXY COMPOUNDS
ANIONS
ARRHENIUS EQUATION
EXPERIMENTAL DATA
FLUORESCENCE
MEDIUM TEMPERATURE
NITROUS OXIDE
RESONANCE ABSORPTION
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
ABSORPTION
CHALCOGENIDES
CHARGED PARTICLES
DATA
EQUATIONS
INFORMATION
IONS
LUMINESCENCE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADICALS
400201* - Chemical & Physicochemical Properties
500100 - Environment
Atmospheric- Basic Studies- (-1989)