Molecular corridors and kinetic regimes in the multiphase chemical evolution of secondary organic aerosol
Molecular corridors and kinetic regimes in the multiphase chemical evolution of secondary organic aerosol
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DOI：
10.5194/acp-14-8323-2014
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发表时间：
2014-08
影响因子：
6.3
通讯作者：
M. Shiraiwa;T. Berkemeier;K. Schilling-Fahnestock;J. Seinfeld;U. Pöschl
中科院分区：
文献类型：
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作者：
M. Shiraiwa;T. Berkemeier;K. Schilling-Fahnestock;J. Seinfeld;U. Pöschl
抽象。大气有机气溶胶的主要成分是来自挥发性有机化合物（VOC）的氧化，即所谓的二次有机气溶胶（SOA）。SOA由大量的有机化合物组成，历史上只有一小部分被识别出来。SOA的形成和演化是一个复杂的过程，涉及气相和颗粒相的化学反应和质量输运耦合。目前的SOA模型没有体现反应和传输过程的全部频谱，也没有确定SOA形成的主要限速步骤。SOA氧化产物的分子鉴定的基础上，我们在这里表明，从各种VOC前体的SOA的化学演变坚持特征“分子走廊”与挥发性和摩尔质量之间的紧密的负相关性。这些走廊的斜率对应于将挥发性降低一个数量级（-dM /dlogC 0）所需的摩尔质量的增加。它在10-30 g mol−1的范围内变化，取决于SOA前体的分子大小和反应产物的O：C比。沿着这些走廊进行的氧化和二聚或低聚的顺序和平行反应途径通过反应限制、扩散限制或扩散限制的多相化学动力学的特征区域，其可以根据反应位置、饱和度和气相和颗粒相的不均匀程度来分类。分子走廊和动力学制度有助于约束和描述的产品，途径和SOA演变的速度的属性，从而促进空气质量和气候的气溶胶模型的进一步发展。
Abstract. The dominant component of atmospheric, organic aerosol is that derived from the oxidation of volatile organic compounds (VOCs), so-called secondary organic aerosol (SOA). SOA consists of a multitude of organic compounds, only a small fraction of which has historically been identified. Formation and evolution of SOA is a complex process involving coupled chemical reaction and mass transport in the gas and particle phases. Current SOA models do not embody the full spectrum of reaction and transport processes, nor do they identify the dominant rate-limiting steps in SOA formation. Based on molecular identification of SOA oxidation products, we show here that the chemical evolution of SOA from a variety of VOC precursors adheres to characteristic "molecular corridors" with a tight inverse correlation between volatility and molar mass. The slope of these corridors corresponds to the increase in molar mass required to decrease volatility by one order of magnitude (-dM / dlogC0). It varies in the range of 10–30 g mol−1, depending on the molecular size of the SOA precursor and the O : C ratio of the reaction products. Sequential and parallel reaction pathways of oxidation and dimerization or oligomerization progressing along these corridors pass through characteristic regimes of reaction-, diffusion-, or accommodation-limited multiphase chemical kinetics that can be classified according to reaction location, degree of saturation, and extent of heterogeneity of gas and particle phases. The molecular corridors and kinetic regimes help to constrain and describe the properties of the products, pathways, and rates of SOA evolution, thereby facilitating the further development of aerosol models for air quality and climate.