A product study of the isoprene+NO3 reaction

Other literature type English OPEN
Perring, A. E. ; Wisthaler, A. ; Graus, M. ; Wooldridge, P. J. ; Lockwood, A. L. ; Mielke, L. H. ; Shepson, P. B. ; Hansel, A. ; Cohen, R. C. (2009)

Oxidation of isoprene through reaction with NO<sub>3</sub> radicals is a significant sink for isoprene that persists after dark. The main products of the reaction are multifunctional nitrates. These nitrates constitute a significant NO<sub>x</sub> sink in the nocturnal boundary layer and they likely play an important role in formation of secondary organic aerosol. Products of the isoprene+NO<sub>3</sub> 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 NO<sub>x</sub>. Product formation in the isoprene + NO<sub>3</sub> 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 65&plusmn;12% of which the majority was nitrooxy carbonyls and the combined yield of methacrolein and methyl vinyl ketone (MACR+MVK) is found to be &sim;10%. PTR-MS measurements of nitrooxy carbonyls and TD-LIF measurements of total organic nitrates agreed well. The PTR-MS also observed a series of minor oxidation products which were tentatively identified and their yields quantified These other oxidation products are used as additional constraints on the reaction mechanism.
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