Atmos. Chem. Phys. Discuss., 8, 8881-8912, 2008
www.atmos-chem-phys-discuss.net/8/8881/2008/
doi:10.5194/acpd-8-8881-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K
S. Vranckx, J. Peeters, and S. A. Carl
University of Leuven, Department of Chemistry, 200F Celestijnenlaan, 3001 Leuven, Belgium

Abstract. We have determined, in the temperature range 227 K to 719 K, the absolute rate constant for the reaction O(1D)+N2O → products and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O(3P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O(1D) that allows for higher precision determinations for both rate constants, and, particularly, O(3P) yields, than do other methods. We found the rate constant, kR1, to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.09)×10−10 cm3 s−1. For temperatures greater than 450 K a marked decrease in value was observed, with a rate constant of only (0.94±0.11)×10−10 cm3 s−1 at 719 K. The rate constants determined over the 227 K–400 K range show very low scatter and are significantly greater, by 20% at room temperature and by 15% at 227 K, than the current recommended values. The fraction of O(3P) produced in this reaction was determined to be 0.002±0.002 at 250 K rising steadily to 0.010±0.004 at 600 K, thus the channel producing O(3P) can be entirely neglected in atmospheric kinetic modeling calculations. A further result of this study is an expression of the relative quantum yields as a function of temperature for the chemiluminescence reactions (kCL1) C2H+O(1D) → CH(A)+CO and (kCL2) C2H+O(3P) → CH(A)+CO, both followed by CH(A) → CH(X)+hν, as kCL1(T)/kCL2(T)=(32.8T−3050)/(6.29T+398).

Citation: Vranckx, S., Peeters, J., and Carl, S. A.: Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K, Atmos. Chem. Phys. Discuss., 8, 8881-8912, doi:10.5194/acpd-8-8881-2008, 2008.
 
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