A statistical description of the evolution of cloud condensation nuclei activity during the heterogeneous oxidation of squalane and bis(2-ethylhexyl) sebacate aerosol by hydroxyl radicals
A statistical description of the evolution of cloud condensation nuclei activity during the heterogeneous oxidation of squalane and bis(2-ethylhexyl) sebacate aerosol by hydroxyl radicals
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DOI：
10.1039/c3cp50347j
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发表时间：
2013-01-01
影响因子：
3.3
通讯作者：
Wilson, Kevin R.
中科院分区：
文献类型：
--
作者：
Harmon, Christopher W.;Ruehl, Christopher R.;Wilson, Kevin R.
羟基自由基与由角鲨烷或双（2-乙基己基）癸二酸酯组成的化学还原有机气溶胶的非均相反应被用作模型系统来研究云凝结核（CCN）活性如何随着光化学氧化而演变。在反应过程中，新的氧官能团的形成和气相反应产物形成的气溶胶大小的变化使临界过饱和发生变化。非均相反应的统计模型表明，正是多代氧化产物的形成、挥发、溶解度和表面活性共同控制了气溶胶吸湿性的平均变化。实验观测和模型表明了考虑粒子内潜在种群或亚种群的重要性，以及它们如何独特地对多组分气溶胶的平均吸湿性作出贡献。为了准确预测氧化后CCN活性的变化，需要通过角鲨烷反应产物亚群降低活化液滴的表面张力。这些结果提供了额外的证据，表明基于宏观数据的表面张力浓度参数化应该对微观液滴进行修改。
The heterogeneous reaction of hydroxyl radicals with chemically reduced organic aerosol comprised of either squalane or bis(2-ethylhexyl) sebacate are used as model systems to examine how cloud condensation nuclei (CCN) activity evolves with photochemical oxidation. Over the course of the reaction, the critical super-saturation evolves both by the formation of new oxygen functional groups and by changes in aerosol size through the formation of gas phase reaction products. A statistical model of the heterogeneous reaction reveals that it is the formation, volatilization, solubility, and surface activity of many generations of oxidation products that together control the average changes in aerosol hygroscopicity. The experimental observations and model demonstrate the importance of considering the underlying population or subpopulation of species within a particle and how they each uniquely contribute to the average hygroscopicity of a multi-component aerosol. To accurately predict changes in CCN activity upon oxidation requires a reduction in the surface tension of the activating droplet by a subpopulation of squalane reaction products. These results provide additional evidence that surface tension-concentration parameterizations based on macroscopic data should be modified for microscopic droplets.