Absolute rate constant and branching fractions for the H + HO/sub 2/ reaction from 245 to 300 K
The total rate constant and the branching fractions for the reactions H + HO/sub 2/ ..-->.. OH + OH (k/sub 1a/), ..-->.. O + H/sub 2/O (k/sub 1b/), ..-->.. H/sub 2/ + O/sub 2/ (k/sub 1c/) have been determined by using resonance fluorescence detection of radical and atomic species. For the total rate constant measurement, pseudo-first-order conditions were used with HO/sub 2/ concentrations in large excess over initial atomic hydrogen. The result is (8.7 +/- 1.5) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/, independent of temperature from 245 to 300 K. For the branching fraction measurements, product yields of OH and atomic oxygen were measured by adding HO/sub 2/ to an excess of atomic hydrogen. Atomic oxygen yields decreased when OH quenchers, such as water or CO, were added. A similar reduction in atomic oxygen yields was observed in the H + NO/sub 2/ reaction. Evidence is presented that the product yields observed with added water are free of interference from secondary reactions. The resulting branching fractions are k/sub 1a//k/sub 1/ = (0.90 +/- 0.04), k/sub 1b//k/sub 1/ = (0.02 +/- 0.02), and k/sub 1c//k/sub 1/ = (0.08 +/- 0.04), independent of temperature from 245 to 300 K.
- Research Organization:
- California Institute of Technology, Pasadena
- OSTI ID:
- 5471229
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 90:13
- Country of Publication:
- United States
- Language:
- English
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PHYSICAL AND ANALYTICAL CHEMISTRY
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HYDROGEN
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
HYDROPEROXY RADICALS
EXPERIMENTAL DATA
MEDIUM TEMPERATURE
RESONANCE FLUORESCENCE
VISIBLE SPECTRA
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400201* - Chemical & Physicochemical Properties
500200 - Environment
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