Dillon, Terry J. orcid.org/0000-0001-8974-9410, Dulitz, Katrin, Groß, Christoph B M et al. (1 more author) (2017) Temperature-dependent rate coefficients for the reactions of the hydroxyl radical with the atmospheric biogenics isoprene, alpha-pinene and delta-3-carene. Atmospheric Chemistry and Physics. pp. 15137-15150. ISSN 1680-7324
Abstract
Pulsed laser methods for OH generation and detection were used to study atmospheric degradation reactions for three important biogenic gases: OHCisoprene (Reaction R1), OH+α-pinene (Reaction R2) and OH+Δ- 3-carene (Reaction R3). Gas-phase rate coefficients were characterized by non-Arrhenius kinetics for all three reactions. For (R1), k1 (241-356 K)= (1:93±0:08)× 10-11 exp{(466±12)/T} cm3 molecule-1 s-1 was determined, with a room temperature value of k1 (297 K)= (9:3± 0:4)×10-11 cm3 molecule-1 s-1, independent of bath-gas pressure (5-200 Torr) and composition (MDN2 or air). Accuracy and precision were enhanced by online optical monitoring of isoprene, with absolute concentrations obtained via an absorption cross section, αisoprene = (1:28±0:06)× 10-17 cm2 molecule-1 at λ = 184:95 nm, determined in this work. These results indicate that significant discrepancies between previous absolute and relative-rate determinations of k1 result in part from σ values used to derive the isoprene concentration in high-precision absolute determinations. Similar methods were used to determine rate coefficients (in 10-11 cm3 molecule-1 s-1/ for (R2)-(R3): k2 (238-357 K)= (1:83±0:04) ×exp{(330±6)/T } and k3 (235-357 K)= (2:48±0:14) ×exp{(357±17)/T }. This is the first temperature-dependent dataset for (R3) and enables the calculation of reliable atmospheric lifetimes with respect to OH removal for e.g. boreal forest springtime conditions. Room temperature values of k2 (296 K)= (5:4±0:2) ×10-11 cm3 molecule-1 s-1 and k3 (297 K)= (8:1±0:3)×10-11 cm3 molecule-1 s-1 were independent of bathgas pressure (7-200 Torr, N2 or air) and in good agreement with previously reported values. In the course of this work, 184.95 nm absorption cross sections were determined: σ = (1:54±0:08) ×10-17 cm2 molecule-1 for α-pinene and (2:40±0:12)×10-17 cm2 molecule-1 for 1-3-carene.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Author(s) 2017. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York The University of York > Faculty of Sciences (York) > Chemistry (York) |
Depositing User: | Pure (York) |
Date Deposited: | 24 Oct 2017 09:30 |
Last Modified: | 02 Nov 2024 01:18 |
Published Version: | https://doi.org/10.5194/acp-17-15137-2017 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.5194/acp-17-15137-2017 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:122956 |
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Description: Temperature dependent rate coefficients for the reactions of the hydroxyl radical with the atmospheric biogenics isoprene, α-pinene and Δ-3-carene
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Description: acp-17-15137-2017