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Secondary organic aerosol (SOA) formation from reaction of isoprene with nitrate radicals (NO_3)

Ng, N. L. and Kwan, A. J. and Surratt, J. D. and Chan, A. W. H. and Chhabra, P. S. and Sorooshian, A. and Pye, H. O. T. and Crounse, J. D. and Wennberg, P. O. and Flagan, R. C. and Seinfeld, J. H. (2008) Secondary organic aerosol (SOA) formation from reaction of isoprene with nitrate radicals (NO_3). Atmospheric Chemistry and Physics Discussions, 8 (1). pp. 3163-3226. ISSN 1680-7367. doi:10.5194/acp-8-4117-2008.

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Secondary organic aerosol (SOA) formation from the reaction of isoprene with nitrate radicals (NO3) is investigated in the Caltech indoor chambers. Experiments are performed in the dark and under dry conditions (RH<10%) using N2O5 as a source of NO3 radicals. For an initial isoprene concentration of 18.4 to 101.6 ppb, the SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) ranges from 4.3% to 23.8%. By examining the time evolutions of gas-phase intermediate products and aerosol volume in real time, we are able to constrain the chemistry that leads to the formation of low-volatility products. Although the formation of ROOR from the reaction of two peroxy radicals (RO2) has generally been considered as a minor channel, based on the gas-phase and aerosol-phase data it appears that RO2+RO2 reaction (self reaction or cross-reaction) in the gas phase yielding ROOR products is a dominant SOA formation pathway. A wide array of organic nitrates and peroxides are identified in the aerosol formed and mechanisms for SOA formation are proposed. Using a uniform SOA yield of 10% (corresponding to Mo≅10 μg m−3), it is estimated that ~2 to 3 Tg yr−1 of SOA results from isoprene + NO3. The extent to which the results from this study can be applied to conditions in the atmosphere depends on the fate of peroxy radicals (i.e. the relative importance of RO2+RO2 versus RO2+NO3 reactions) in the nighttime troposphere.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ng, N. L.0000-0001-8460-4765
Surratt, J. D.0000-0002-6833-1450
Chan, A. W. H.0000-0001-7392-4237
Sorooshian, A.0000-0002-2243-2264
Pye, H. O. T.0000-0002-2014-2140
Crounse, J. D.0000-0001-5443-729X
Wennberg, P. O.0000-0002-6126-3854
Flagan, R. C.0000-0001-5690-770X
Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© Author(s) 2008. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 3 January 2008 – Accepted: 10 January 2008 – Published: 15 February 2008. This research was funded by U.S. Department of Energy Biological and Environmental Research Program DE-FG02-05ER63983. This material is based in part on work supported by the National Science Foundation (NSF) under grant ATM-0432377. The Waters LCT Premier XT time-of-flight mass spectrometer interfaced to a Waters UPLC system was purchased in 2006 with a grant from the National Science Foundation, Chemistry Research Instrumentation and Facilities Program (CHE-0541745). The LCQ Ion Trap mass spectrometer was purchased in 1997 with funds from the National Science Foundation through the CRIF program (CHE-9709233). J.D. Surratt 5 is supported in part by the U.S. EPA under the STAR Graduate Fellowship Program. A.J. Kwan acknowledges the support of a NSF graduate research fellowship. The authors would like to thank C.D. Vecitis, J. Cheng, and M.R. Hoffmann for use of and aid with their ozonizer and UV-VIS spectrometer; to K. Takematsu and M. Okumura for helpful advice on preparing N2O5; to J.H. Kroll and M. Claeys for helpful discussions and suggestions; and to M.N. Chan for assistance with filter sample collection.
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Department of Energy (DOE)DE-FG02-05ER63983
Environmental Protection Agency (EPA)UNSPECIFIED
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Record Number:CaltechAUTHORS:NGNacpd08
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Usage Policy:This work is distributed under the Creative Commons Attribution 3.0 License.
ID Code:12035
Deposited By: Archive Administrator
Deposited On:21 Oct 2008 00:43
Last Modified:08 Nov 2021 22:25

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