Secondary organic aerosol formation from isoprene photooxidation
Secondary organic aerosol formation from isoprene photooxidation
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DOI：
10.1021/es0524301
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发表时间：
2006-03-15
影响因子：
11.4
通讯作者：
Seinfeld, JH
中科院分区：
文献类型：
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作者：
Kroll, JH;Ng, NL;Seinfeld, JH
近期的研究表明，异戊二烯（2 - 甲基 - 1,3 - 丁二烯，C₅H₈）的大气氧化会导致二次有机气溶胶（SOA）的形成。在这项研究中，通过在一系列实验条件下，即不同的异戊二烯和NOₓ浓度下测量SOA的产率，对异戊二烯光氧化形成SOA的机制进行了全面研究。过氧化氢被用作自由基前体，这在很大程度上限制了所观测到的气相化学过程；所有的氧化过程都由OH自由基主导，并且有机过氧自由基（RO₂）仅与HO₂（在OH + H₂O₂反应中形成）或NO反应，包括无NOₓ的条件。在高NOₓ条件下，发现产率随着[NOₓ]的增加而大幅降低，这表明RO₂化学在SOA形成过程中的重要性。在低NOₓ条件下，观察到SOA质量迅速下降，这是半挥发性SOA成分发生化学反应的结果，很可能是有机氢过氧化物的反应。
Recent work has shown that the atmospheric oxidation of isoprene (2-methyl-1,3-butadiene, C5H8) 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., 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 (RO2) react only with HO2 (formed in the OH + H2O2 reaction) or NO concentrations, including NOx-free conditions. At high NOx, 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.