Hydroxy nitrate production in the OH-initiated oxidation of alkenes

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dc.contributor.authorTeng, A. P.
dc.contributor.authorCrounse, J.D.
dc.contributor.authorLee, L.
dc.contributor.authorSt. Clair, Jason
dc.contributor.authorCohen, R.C.
dc.contributor.authorWennberg, P. O.
dc.date.accessioned2020-06-17T16:55:49Z
dc.date.available2020-06-17T16:55:49Z
dc.date.issued2015-04-28
dc.description.abstractAlkenes are oxidized rapidly in the atmosphere by addition of OH and subsequently O₂ leading to the formation of β-hydroxy peroxy radicals. These peroxy radicals react with NO to form β-hydroxy nitrates with a branching ratio α. We quantify α for C₂–C₈ alkenes at 295 K ± 3 and 993 hPa. The branching ratio can be expressed as α = (0.045 ± 0.016) × N − (0.11 ± 0.05) where N is the number of heavy atoms (excluding the peroxy moiety), and listed errors are 2σ. These branching ratios are larger than previously reported and are similar to those for peroxy radicals formed from H abstraction from alkanes. We find the isomer distributions of β-hydroxy nitrates formed under NO-dominated peroxy radical chemistry to be different than the isomer distribution of hydroxy hydroperoxides produced under HO₂-dominated peroxy radical chemistry. Assuming unity yield for the hydroperoxides implies that the branching ratio to form β-hydroxy nitrates increases with substitution of RO₂. Deuterium substitution enhances the branching ratio to form hydroxy nitrates in both propene and isoprene by a factor of ~ 1.5. The role of alkene chemistry in the Houston region is re-evaluated using the RONO₂ branching ratios reported here. Small alkenes are found to play a significant role in present-day oxidant formation more than a decade (2013) after the 2000 Texas Air Quality Study identified these compounds as major contributors to photochemical smog in Houston.en_US
dc.description.sponsorshipThe authors thank T. Ryerson, I. B. Pollack, and J. Peischl at NOAA ESRL for ozone observations and T. F. Hanisco and G. M. Wolfe at NASA for formaldehyde observations from the NASA SEAC4RS flight on 18 September 2013. We acknowledge grant funding from the National Science Foundation (NSF) under grant AGS-1240604 and funding from the National Aeronautics and Space Administration (NASA) under grant NNX12AC06G and NNX14AP46G-ACCDAM.en_US
dc.description.urihttps://www.atmos-chem-phys.net/15/4297/2015/en_US
dc.format.extent20 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2t6ov-4kqs
dc.identifier.citationTeng, A. P., Crounse, J. D., Lee, L., St. Clair, J. M., Cohen, R. C., and Wennberg, P. O.: Hydroxy nitrate production in the OH-initiated oxidation of alkenes, Atmos. Chem. Phys., 15, 4297–4316, https://doi.org/10.5194/acp-15-4297-2015, 2015.en_US
dc.identifier.urihttps://doi.org/10.5194/acp-15-4297-2015
dc.identifier.urihttp://hdl.handle.net/11603/18913
dc.language.isoen_USen_US
dc.publisherCopernicus Publicationsen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.titleHydroxy nitrate production in the OH-initiated oxidation of alkenesen_US
dc.typeTexten_US

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