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| Titel |
Temperature dependence of carbon kinetic isotope effect for the oxidation reaction of ethane by OH radicals under atmospherically relevant conditions |
| VerfasserIn |
Tammarat Piansawan, Marina Saccon, Werner Laumer, Iulia Gensch, Astrid Kiendler-Scharr |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106907
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| Publikation (Nr.) |
 EGU/EGU2015-6590.pdf |
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| Zusammenfassung |
| Modeling of the global distribution of atmospheric ethane sources and sinks
by using the $^{13}$C isotopic composition requires accurate knowledge of
the carbon kinetic isotope effect (KIE) of its atmospheric removal
reactions. The quantum mechanical prediction
implies the necessity to elucidate the temperature dependence of KIE within
atmospherically relevant temperature range by experiment. In this study, the
KIE and its temperature dependence for ethane oxidation by OH radicals was
investigated at ambient pressure in a temperature range of 243 K to 303 K.
The chemical reactions were carried out in a 15 L PFE reaction chamber,
suspended in a thermally controlled oven. The isotope ratios of the gas
phase components during the course of the reactions were measured by Thermal
Desorption -- Gas Chromatography -- Isotope Ratio Mass Spectrometry
(TD-GC-IRMS). For each temperature, the KIE was derived from the temporal
evolution of the concentration and stable carbon isotope ratio (\delta$^{13}$C)
of ethane using a method adapted from the relative reaction rate concept.
The room temperature KIE of the ethane reaction with OH radicals was found
to be 6.85 $\pm $ 0.32 \permil. This value is in agreement with
the previously reported value of 8.57 $\pm $ 1.95 \permil
[Anderson et al. 2004] but has a substantially lower uncertainty. The
experimental results will be discussed with the KIE temperature dependence
predicted by quantum mechanical calculations.
Reference: Rebecca S. Anderson, Lin Huang, Richard Iannone, Alexandra E.
Thompson, and Jochen Rudolph (2004), Carbon Kinetic Isotope Effects in the
Gas Phase Reactions of Light Alkanes and Ethene with the OH Radical at 296
$\pm $ 4 K, \textit{J. Phys. Chem. A}, $108,$ 11537--11544 |
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