Flash photolysis of water vapor in methane. Hydrogen and hydroxyl yields and rate constants for methyl reactions with hydrogen and hydroxyl

.. CH/sub 4/) = (1.2 +- 0.3) x 10/sup 11/ M/sup -1/ s/sup -1/; k/sub 8/(OH + CH/sub 3/ + M ..-->.. products) = (5.6 +-more » 1.5) x 10/sup 10/ M/sup -1/ s/sup -1/; k/sub 2/(OH + CH/sub 4/ ..-->.. CH/sub 3/ + H/sub 2/O) = (4.2 +- 0.4) x 10/sup 6/ M/sup -1/ s/sup -1/; and k/sub 5/(OH + H/sub 2/ ..-->.. H + H/sub 2/O) = (5.1 +- 1.1) x 10/sup 6/ M/sup -1/ s/sup -1/. The error limits were determined by sensitivity analysis. Information on water dissociation yields under these conditions permits the use of water vapor as a calibrated radical source for the study of other important systems. 29 references, 5 figures, 3 tables.« less -->
ISSN: 1541-5740
0022-3654
DOI: 10.1021/j100439a002
Přístupová URL adresa: https://explore.openaire.eu/search/publication?articleId=doi_________::310291b0d795ee134cce86bcf83839ff
https://doi.org/10.1021/j100439a002
Přírůstkové číslo: edsair.doi...........310291b0d795ee134cce86bcf83839ff
Autor: T. J. Sworski, C. J. Hochanadel, P. J. Ogren
Rok vydání: 1980
Předmět:
Zdroj: The Journal of Physical Chemistry. 84:129-134
ISSN: 1541-5740
0022-3654
DOI: 10.1021/j100439a002
Popis: Methyl radicals, generated by reaction of CH/sub 4/ with OH radicals from the flash photolysis of water vapor, decay by reaction with H, OH, and CH/sub 3/. The concentration of CH/sub 3/ is followed by monitoring the absorption at 216 nm: use of the previously determined values of (3.1 +- 0.6) x 10/sup 10/ M/sup -1/ s/sup -1/ for k/sub 3/(CH/sub 3/ + CH/sub 3/) and epsilon(CH/sub 3/) = 9000 +- 800 M/sup -1/ cm/sup -1/ at this wavelength for a 0.6-nm bandwidth permits calculation of the amount of water dissociated per flash and the values of several rate constants. Measurements were made as a function of CH/sub 4/ concentration by using N/sub 2/ and H/sub 2/ as diluents at atmospheric pressure. When numerical modeling was used to fit the CH/sub 3/ data by the method of least squares, it was found that 0.9 x 10/sup -6/ M OH and H concentrations are produced under typical operating conditions. The following absolute rate constants (296 K) were obtained: k/sub 4/(H + CH/sub 3/ + M ..-->.. CH/sub 4/) = (1.2 +- 0.3) x 10/sup 11/ M/sup -1/ s/sup -1/; k/sub 8/(OH + CH/sub 3/ + M ..-->.. products) = (5.6 +-more » 1.5) x 10/sup 10/ M/sup -1/ s/sup -1/; k/sub 2/(OH + CH/sub 4/ ..-->.. CH/sub 3/ + H/sub 2/O) = (4.2 +- 0.4) x 10/sup 6/ M/sup -1/ s/sup -1/; and k/sub 5/(OH + H/sub 2/ ..-->.. H + H/sub 2/O) = (5.1 +- 1.1) x 10/sup 6/ M/sup -1/ s/sup -1/. The error limits were determined by sensitivity analysis. Information on water dissociation yields under these conditions permits the use of water vapor as a calibrated radical source for the study of other important systems. 29 references, 5 figures, 3 tables.« less
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