Atmos. Chem. Phys. Discuss., 9, 5231-5261, 2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
A product study of the isoprene+NO3 reaction
A. E. Perring1, A. Wisthaler2,*, M. Graus2, P. J. Wooldridge1, A. L. Lockwood4, L. H. Mielke4, P. B. Shepson3,4, A. Hansel2, and R. C. Cohen1,5
1Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
2Institut fuer Ionenphysik und Angewandte Physik, University of Innsbruck, Innsbruck, Austria
3Purdue Climate Change Research Center, Purdue University, West Lafayette, IN, USA
4Department of Chemistry, Purdue University, West Lafayette, IN, USA
5Department of Earth and Planetary Sciences, University of California Berkeley, Berkeley, CA, USA
*equally contributing author

Abstract. Oxidation of isoprene through reaction with NO3 is a significant sink for isoprene that persists after dark. The products of the reaction are multifunctional nitrates. These nitrates constitute a significant NOx sink in the nocturnal boundary layer and they likely play an important role in formation of secondary organic aerosol. Products of the isoprene+NO3 reaction will, in many locations, be abundant enough to affect nighttime radical chemistry and to persist into daytime where they may represent a source of NOx. Product formation in the isoprene+NO3 reaction was studied in a smog chamber at Purdue University. Isoprene nitrates and other hydrocarbon products were observed using Proton Transfer Reaction-Mass Spectrometry (PTR-MS) and reactive nitrogen products were observed using Thermal Dissociation–Laser Induced Fluorescence (TD-LIF). The organic nitrate yield is found to be 62±6% and the combined yield of MACR+MVK is found to be ~10%. Additional hydrocarbon products, thought to be primarily C4 and C5 carbonyl compounds, were observed by the PTR-MS at various m/z ratios and their yields quantified. These other oxidation products are used as additional constraints on the reaction mechanism.

Citation: Perring, A. E., Wisthaler, A., Graus, M., Wooldridge, P. J., Lockwood, A. L., Mielke, L. H., Shepson, P. B., Hansel, A., and Cohen, R. C.: A product study of the isoprene+NO3 reaction, Atmos. Chem. Phys. Discuss., 9, 5231-5261, doi:10.5194/acpd-9-5231-2009, 2009.
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