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Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene

Nguyen, Tran B. and Tyndall, Geoffrey S. and Crounse, John D. and Teng, Alexander P. and Bates, Kelvin H. and Schwantes, Rebecca H. and Coggon, Matthew M. and Zhang, Li and Feiner, Philip and Milller, David O. and Skog, Kate M. and Rivera-Rios, Jean C. and Dorris, Matthew and Olson, Kevin F. and Koss, Abigail and Wild, Robert J. and Brown, Steven S. and Goldstein, Allen H. and de Gouw, Joost A. and Brune, William H. and Keutsch, Frank N. and Seinfeld, John H. and Wennberg, Paul O. (2016) Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene. Physical Chemistry Chemical Physics, 18 (15). pp. 10241-10254. ISSN 1463-9076. http://resolver.caltech.edu/CaltechAUTHORS:20160404-151740437

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Abstract

We use a large laboratory, modeling, and field dataset to investigate the isoprene + O_3 reaction, with the goal of better understanding the fates of the C_1 and C_4 Criegee intermediates in the atmosphere. Although ozonolysis can produce several distinct Criegee intermediates, the C_1 stabilized Criegee (CH_2OO, 61 ± 9%) is the only one observed to react bimolecularly. We suggest that the C_4 Criegees have a low stabilization fraction and propose pathways for their decomposition. Both prompt and non-prompt reactions are important in the production of OH (28% ± 5%) and formaldehyde (81% ± 16%). The yields of unimolecular products (OH, formaldehyde, methacrolein (42 ± 6%) and methyl vinyl ketone (18 ± 6%)) are fairly insensitive to water, i.e., changes in yields in response to water vapor (≤4% absolute) are within the error of the analysis. We propose a comprehensive reaction mechanism that can be incorporated into atmospheric models, which reproduces laboratory data over a wide range of relative humidities. The mechanism proposes that CH_2OO + H_2O (k_((H_2O)) ∼ 1 × 10^(−15) cm^3 molec^(−1) s^(−1)) yields 73% hydroxymethyl hydroperoxide (HMHP), 6% formaldehyde + H_2O_2, and 21% formic acid + H_2O; and CH_2OO + (H_2O)_2 (k_((H_2O)_2) ∼ 1 × 10^(−12) cm^3 molec^(−1) s^(−1)) yields 40% HMHP, 6% formaldehyde + H_2O_2, and 54% formic acid + H_2O. Competitive rate determinations (k_(SO_2/k(H_2O)n=1,2) ∼ 2.2 (±0.3) × 10^4) and field observations suggest that water vapor is a sink for greater than 98% of CH2OO in a Southeastern US forest, even during pollution episodes ([SO_2] ∼ 10 ppb). The importance of the CH_2OO + (H_2O)n reaction is demonstrated by high HMHP mixing ratios observed over the forest canopy. We find that CH_2OO does not substantially affect the lifetime of SO_2 or HCOOH in the Southeast US, e.g., CH_2OO + SO_2 reaction is a minor contribution (<6%) to sulfate formation. Extrapolating, these results imply that sulfate production by stabilized Criegees is likely unimportant in regions dominated by the reactivity of ozone with isoprene. In contrast, hydroperoxide, organic acid, and formaldehyde formation from isoprene ozonolysis in those areas may be significant.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1039/C6CP00053C DOIArticle
http://pubs.rsc.org/en/Content/ArticleLanding/2016/CP/C6CP00053CPublisherArticle
http://www.rsc.org/suppdata/c6/cp/c6cp00053c/c6cp00053c1.pdfPublisherSupplementary Information
ORCID:
AuthorORCID
Crounse, John D.0000-0001-5443-729X
Bates, Kelvin H.0000-0001-7544-9580
Schwantes, Rebecca H.0000-0002-7095-3718
Coggon, Matthew M.0000-0002-5763-1925
Seinfeld, John H.0000-0003-1344-4068
Wennberg, Paul O.0000-0002-6126-3854
Additional Information:© 2016 Owner Societies. Received 4th January 2016, Accepted 16th March 2016. First published online 16 Mar 2016. Funding for this work was provided by the U.S. National Science Foundation (NSF) Postdoctoral Research Fellowship award AGS-1331360, NSF grant AGS-1240604, and the Electric Power Research Institute grant EPRI-10003903. We thank the organizers and participants of the FIXCIT chamber campaign and SOAS field campaign.
Funders:
Funding AgencyGrant Number
NSF Postdoctoral FellowshipAGS-1331360
NSFAGS-1240604
Electric Power Research Institute (EPRI)EPRI-10003903
Record Number:CaltechAUTHORS:20160404-151740437
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160404-151740437
Official Citation:Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene Tran B. Nguyen, Geoffrey S. Tyndall, John D. Crounse, Alexander P. Teng, Kelvin H. Bates, Rebecca H. Schwantes, Matthew M. Coggon, Li Zhang, Philip Feiner, David O. Milller, Kate M. Skog, Jean C. Rivera-Rios, Matthew Dorris, Kevin F. Olson, Abigail Koss, Robert J. Wild, Steven S. Brown, Allen H. Goldstein, Joost A. de Gouw, William H. Brune, Frank N. Keutsch, John H. Seinfeld and Paul O. Wennberg Phys. Chem. Chem. Phys., 2016, 18, 10241-10254 DOI: 10.1039/C6CP00053C
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65907
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Apr 2016 21:55
Last Modified:02 May 2017 23:09

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