Secondary Organic Aerosol Formation from Isoprene Photooxidation
Abstract
Recent work has shown that the atmospheric oxidation of isoprene (2-methyl-1,3-butadiene, C_5H_8) leads to the formation of secondary organic aerosol (SOA). In this study, the mechanism of SOA formation by isoprene photooxidation is comprehensively investigated, by measurements of SOA yields over a range of experimental conditions, namely isoprene and NO_x concentrations. Hydrogen peroxide is used as the radical precursor, substantially constraining the observed gas-phase chemistry; all oxidation is dominated by the OH radical, and organic peroxy radicals (RO_2) react only with HO_2 (formed in the OH + H_2O_2 reaction) or NO concentrations, including NO_x-free conditions. At high NO_x, yields are found to decrease substantially with increasing [NOx], indicating the importance of RO2 chemistry in SOA formation. Under low-NOx conditions, SOA mass is observed to decay rapidly, a result of chemical reactions of semivolatile SOA components, most likely organic hydroperoxides.
Additional Information
© 2006 American Chemical Society. Received for review December 3, 2005. Revised manuscript received January 13, 2006. Accepted January 18, 2006. Publication Date (Web): February 15, 2006. This research was funded by the U.S. Environmental Protection Agency Science to Achieve Results (STAR) Program grant number RD-83107501-0, managed by EPA's Office of Research and Development (ORD), National Center for Environmental Research (NCER), and by the U.S. Department of Energy Biological and Environmental Research Program DE-FG03-01ER63099; this work has not been subjected to the EPA's required peer and policy review and, therefore, does not necessarily reflect the views of the Agency and no official endorsement should be inferred.Attached Files
Supplemental Material - es0524301si20051203_063924.pdf
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Additional details
- Eprint ID
- 68533
- Resolver ID
- CaltechAUTHORS:20160620-124956898
- RD-83107501-0
- Environmental Protection Agency (EPA)
- DE-FG03-01ER63099
- Department of Energy (DOE)
- Created
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2016-06-20Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field