Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes

<p>The rate coefficients of the reaction of hydroxyl radicals (<span class="inline-formula">OH</span>) with 12 different volatile organic compounds (<span class="inline-formula">VOCs</span>), namely methane, ethane, propane, <span class="inli...

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Main Authors: F. Berg, A. Novelli, R. Dubus, A. Hofzumahaus, F. Holland, A. Wahner, H. Fuchs
Format: Article
Language:English
Published: Copernicus Publications 2024-12-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/24/13715/2024/acp-24-13715-2024.pdf
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author F. Berg
A. Novelli
R. Dubus
A. Hofzumahaus
F. Holland
A. Wahner
H. Fuchs
H. Fuchs
author_facet F. Berg
A. Novelli
R. Dubus
A. Hofzumahaus
F. Holland
A. Wahner
H. Fuchs
H. Fuchs
author_sort F. Berg
collection DOAJ
description <p>The rate coefficients of the reaction of hydroxyl radicals (<span class="inline-formula">OH</span>) with 12 different volatile organic compounds (<span class="inline-formula">VOCs</span>), namely methane, ethane, propane, <span class="inline-formula"><i>n</i></span>-butane, methyl vinyl ketone (MVK), <span class="inline-formula"><i>γ</i></span>-terpinene, <span class="inline-formula">Δ<sup>3</sup></span>-carene, myrcene, toluene, <span class="inline-formula"><i>o</i></span>-xylene, <span class="inline-formula"><i>m</i></span>-xylene, and mesitylene, were studied in an absolute rate study in 1 <span class="inline-formula">atm</span> of air between 280 and 340 <span class="inline-formula">K</span> using an <span class="inline-formula">OH</span> reactivity instrument with a temperature-controlled flow tube. There are few or no measurements in the literature for the important monoterpene and aromatic compounds emitted by biogenic and anthropogenic sources, although the oxidation of these species is particularly important in the formation of secondary pollutants such as ozone and particles. The time-dependent decay of the <span class="inline-formula">OH</span> concentration was measured in a flow tube, allowing the pseudo-first-order rate coefficient to be determined after the production of a moderately high <span class="inline-formula">OH</span> concentration (about <span class="inline-formula">1×10<sup>9</sup></span> <span class="inline-formula">cm<sup>−3</sup></span>) by the photolysis of ozone in the presence of water vapour. In contrast to many previous studies, the <span class="inline-formula">OH</span> reaction took place in a volume at ambient conditions, while the detection of <span class="inline-formula">OH</span> was achieved by fluorescence in a separate low-pressure detection volume. The <span class="inline-formula">VOC</span> concentrations were measured using the total organic carbon method. With the methods used, a high accuracy of the rate constants is obtained (<span class="inline-formula">2<i>σ</i></span> uncertainties approximately 6 %).</p>
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spelling doaj-art-3b139a93339544eb9ff0c2bd3d9df9222024-12-12T05:47:28ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242024-12-0124137151373110.5194/acp-24-13715-2024Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenesF. Berg0A. Novelli1R. Dubus2A. Hofzumahaus3F. Holland4A. Wahner5H. Fuchs6H. Fuchs7Institute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute of Climate and Energy Systems, ICE-3: Troposphere, Forschungszentrum Jülich GmbH, Jülich, GermanyDepartment of Physics, University of Cologne, Cologne, Germany<p>The rate coefficients of the reaction of hydroxyl radicals (<span class="inline-formula">OH</span>) with 12 different volatile organic compounds (<span class="inline-formula">VOCs</span>), namely methane, ethane, propane, <span class="inline-formula"><i>n</i></span>-butane, methyl vinyl ketone (MVK), <span class="inline-formula"><i>γ</i></span>-terpinene, <span class="inline-formula">Δ<sup>3</sup></span>-carene, myrcene, toluene, <span class="inline-formula"><i>o</i></span>-xylene, <span class="inline-formula"><i>m</i></span>-xylene, and mesitylene, were studied in an absolute rate study in 1 <span class="inline-formula">atm</span> of air between 280 and 340 <span class="inline-formula">K</span> using an <span class="inline-formula">OH</span> reactivity instrument with a temperature-controlled flow tube. There are few or no measurements in the literature for the important monoterpene and aromatic compounds emitted by biogenic and anthropogenic sources, although the oxidation of these species is particularly important in the formation of secondary pollutants such as ozone and particles. The time-dependent decay of the <span class="inline-formula">OH</span> concentration was measured in a flow tube, allowing the pseudo-first-order rate coefficient to be determined after the production of a moderately high <span class="inline-formula">OH</span> concentration (about <span class="inline-formula">1×10<sup>9</sup></span> <span class="inline-formula">cm<sup>−3</sup></span>) by the photolysis of ozone in the presence of water vapour. In contrast to many previous studies, the <span class="inline-formula">OH</span> reaction took place in a volume at ambient conditions, while the detection of <span class="inline-formula">OH</span> was achieved by fluorescence in a separate low-pressure detection volume. The <span class="inline-formula">VOC</span> concentrations were measured using the total organic carbon method. With the methods used, a high accuracy of the rate constants is obtained (<span class="inline-formula">2<i>σ</i></span> uncertainties approximately 6 %).</p>https://acp.copernicus.org/articles/24/13715/2024/acp-24-13715-2024.pdf
spellingShingle F. Berg
A. Novelli
R. Dubus
A. Hofzumahaus
F. Holland
A. Wahner
H. Fuchs
H. Fuchs
Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
Atmospheric Chemistry and Physics
title Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
title_full Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
title_fullStr Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
title_full_unstemmed Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
title_short Temperature-dependent rate coefficients for the reactions of OH radicals with selected alkanes, aromatic compounds, and monoterpenes
title_sort temperature dependent rate coefficients for the reactions of oh radicals with selected alkanes aromatic compounds and monoterpenes
url https://acp.copernicus.org/articles/24/13715/2024/acp-24-13715-2024.pdf
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