Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K
Item
Title (Dublin Core)
Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K
Description (Dublin Core)
The absolute rate constant for the reaction that is the major source of stratospheric NO<sub>x</sub>, O(<sup>1</sup>D)+N<sub>2</sub>O → products, has been determined in the temperature range 227 K to 719 K, and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O(<sup>3</sup>P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O(<sup>1</sup>D) that allows for higher precision determinations for both rate constants, and, particularly, O(<sup>3</sup>P) yields, than do other methods. We found the rate constant, <i>k</i><sub>R1</sub>, to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.11)×10<sup>−10</sup> cm<sup>3</sup> s<sup>−1</sup>, and for temperatures greater than 450 K a marked decrease in rate constant was observed, with a rate constant of only (0.94±0.11)×10<sup>−10</sup> cm<sup>3</sup> s<sup>−1</sup> 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 15% at 227 K, than the current recommended values. The fraction of O(<sup>3</sup>P) 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(<sup>3</sup>P) 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 (<i>k<sub>CL1</sub></i>)C<sub>2</sub>H + O(<sup>1</sup>D) → CH(A) + CO and (<i>k<sub>CL2</sub></i>)C<sub>2</sub>H + O(<sup>3</sup>P) → CH(A) + CO, both followed by CH(A) → CH(X) + <i>h</i>ν, as <i>k<sub>CL1</sub>(T)/k<sub>CL2</sub>(T)</i>=(32.8<i>T</i>−3050)/(6.29<i>T</i>+398).
Creator (Dublin Core)
Vranckx, S.
Peeters, J.
Carl, S. A.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-8-6261-2008
https://acp.copernicus.org/articles/8/6261/2008/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
