Complex refractive index of secondary organic aerosol generated from isoprene/NOx photooxidation in the presence and absence of SO2
Complex refractive index of secondary organic aerosol generated from isoprene/NOx photooxidation in the presence and absence of SO2
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DOI：
10.1002/2015jd023522
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
T. Nakayama;Kei Sato;M. Tsuge;T. Imamura;Y. Matsumi
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文献类型：
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作者：
T. Nakayama;Kei Sato;M. Tsuge;T. Imamura;Y. Matsumi
我们报告的复折射率（RI）在375，405，532，和781 nm的二次有机气溶胶（SOA）产生的异戊二烯/NOx光氧化的第一次测量。在所有的波长研究，略大的真实的组件的RI观察到的SOA中产生的SO2的情况下，与那些产生在其存在。考虑到化学性质，SOA中化合物的氧化态和/或颗粒密度与分子量之比的差异被认为是决定真实的组分的主要因素。在≤532 nm处的虚部随初始SO2浓度的增加而增加。高度共轭的低聚物被认为是合理的发色团候选者。这项研究表明，当异戊二烯与NOx和SOx混合后产生大量的SOA时，这些SOA的光吸收可能会与炭黑竞争，特别是在紫外波长处。
We report the first measurements of the complex refractive index (RI) at 375, 405, 532, and 781 nm for secondary organic aerosol (SOA) generated from isoprene/NOx photooxidation. At all wavelengths studied, slightly greater real components of the RI were observed for the SOA generated in the absence of SO2 compared with those generated in its presence. Considering the chemical properties, the differences in the oxidation state and/or ratio of particle density to molecular weight of compounds in the SOA are considered to be the main factors determining the real components. The imaginary components at ≤532 nm were found to increase with increasing initial SO2 concentration. The highly conjugated oligomers are suggested to be plausible chromophore candidates. This study suggests that when large amounts of SOA are generated after mixing of isoprene with NOx and SOx, light absorption of these SOAs may compete with that of black carbon, especially at ultraviolet wavelengths.