Secondary Organic Aerosol Formation from Isoprene Photooxidation

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• 作者：Jesse H. Kroll ; Nga L. Ng ; Shane M. Murphy ; Richard C. Flagan ; and John H. Seinfeld
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：March 15, 2006
• 年：2006
• 卷：40
• 期：6
• 页码：1869 - 1877
• 全文大小：573K
• 年卷期：v.40,no.6(March 15, 2006)
• ISSN：1520-5851

文摘

Recent work has shown that the atmospheric oxidation ofisoprene (2-methyl-1,3-butadiene, C₅H₈) leads to theformation of secondary organic aerosol (SOA). In thisstudy, the mechanism of SOA formation by isoprenephotooxidation is comprehensively investigated, bymeasurements of SOA yields over a range of experimentalconditions, 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 organicperoxy radicals (RO₂) react only with HO₂ (formed in the OH+ H₂O₂ reaction) or NO concentrations, including NO_x-free conditions. At high NO_x, yields are found to decreasesubstantially with increasing [NO_x], indicating theimportance of RO₂ chemistry in SOA formation. Under low-NO_x conditions, SOA mass is observed to decay rapidly,a result of chemical reactions of semivolatile SOA components,most likely organic hydroperoxides.