Alkoxy Radical Bond Scissions Explain the Anomalously Low Secondary Organic Aerosol and Organonitrate Yields from α-Pinene + NO_3
Abstract
Oxidation of monoterpenes (C_(10)H_(16)) by nitrate radicals (NO_3) constitutes an important source of atmospheric secondary organic aerosol (SOA) and organonitrates. However, knowledge of the mechanisms of their formation is incomplete and differences in yields between similar monoterpenes are poorly understood. In particular, yields of SOA and organonitrates from α-pinene + NO_3 are low, while those from Δ^3-carene + NO_3 are high. Using computational methods, we suggest that bond scission of the nitrooxy alkoxy radicals from Δ^3-carene lead to the formation of reactive keto-nitrooxy-alkyl radicals, which retain the nitrooxy moiety and can undergo further reactions to form SOA. In contrast, bond scissions of the nitrooxy alkoxy radicals from α-pinene lead almost exclusively to the formation of the relatively unreactive and volatile product pinonaldehyde (C_(10)H_(16)O_2), thereby limiting organonitrate and SOA formation. This hypothesis is supported by laboratory experiments that quantify products of the reaction of α-pinene + NO_3 under atmospherically relevant conditions.
Additional Information
© 2017 American Chemical Society. This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: April 28, 2017; Accepted: June 6, 2017; Published: June 6, 2017. From the FIXCIT campaign, we thank Matthew Coggon and John Seinfeld for AMS data, Jeong-Hoo Park, Allen Goldstein, John Mak, and Alex Guenther for the PTR-MS data, John Crounse, Alex Teng and Kelvin Bates for the ToF-CIMS data and their work organizing and conducting the experiment. We also thank Alan Shusterman, Catherine Neshyba, Katie Stellmach, Rasmus V. Otkjær, Noora Hyttinen, Camilla Mia Tram, and Benjamin N. Frandsen for helpful discussions. TK thanks the Academy of Finland (266388) for funding and the CSC IT Center for Science in Espoo, Finland, for computing time. HGK and KHM thank the Center for Exploitation of Solar Energy, University of Copenhagen and the Danish Center for Scientific Computing for funding. POW thanks the NSF for funding (Grant No. CHE-1508526 and AGS-1240604). JLF gratefully acknowledges sabbatical support from the U.S. Fulbright Scholar Program and research funding from the NOAA Climate Program Office's AC4 program (Grant No. NA13OAR4310070). The National Center for Atmospheric Research is sponsored by the National Science Foundation.Attached Files
Published - acs.jpclett.7b01038.pdf
Supplemental Material - jz7b01038_si_001.pdf
Supplemental Material - jz7b01038_si_002.zip
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Additional details
- Eprint ID
- 78031
- DOI
- 10.1021/acs.jpclett.7b01038
- Resolver ID
- CaltechAUTHORS:20170608-112307794
- 266388
- Academy of Finland
- University of Copenhagen
- Danish Center for Scientific Computing
- CHE-1508526
- NSF
- AGS-1240604
- NSF
- Fulbright Foundation
- NA13OAR4310070
- National Oceanic and Atmospheric Administration (NOAA)
- Created
-
2017-06-08Created from EPrint's datestamp field
- Updated
-
2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences