Halogen-induced organic aerosol (XOA): a study on ultra-fine particle formation and time-resolved chemical characterization.
Halogen-induced organic aerosol (XOA): a study on ultra-fine particle formation and time-resolved chemical characterization.
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DOI：
10.1039/c3fd00093a
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发表时间：
2013-12
影响因子：
3.4
通讯作者：
J. Ofner;K. Kamilli;A. Held;B. Lendl;C. Zetzsch
中科院分区：
文献类型：
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作者：
J. Ofner;K. Kamilli;A. Held;B. Lendl;C. Zetzsch
同时存在的高值的有机SOA前体和活性卤素物种（RHS）在非常低的臭氧浓度允许卤素诱导的有机气溶胶，所谓的XOA的形成，在海洋区域，其中存在高浓度的RHS，特别是在日出。本研究结合气溶胶烟雾室和气溶胶流动反应器实验XOA的表征。XOA的形成产率从α-蒎烯在低浓度和高浓度的氯作为活性卤素物种（RHS）的测定使用700 L气溶胶烟雾室与太阳模拟器。利用气溶胶流动反应器和傅立叶变换红外光谱仪研究了气溶胶形成过程和化学老化过程中有机前体物的化学转化。使用2D相关光谱分析FTIR数据集。氯诱导的均匀XOA形成甚至在2.5ppb的分子氯下发生，其被太阳模拟器光解。XOA形成的化学途径的特征在于加入氯和夺取氢原子，导致同时形成碳-氯键。在形成过程的进一步步骤中，形成羧酸，这导致XOA的SOA样外观。二次有机气溶胶与RHS的无臭氧形成过程中，形成了一种特殊的颗粒物（XOA），然后通过大气老化或降解途径转化为SOA。
The concurrent presence of high values of organic SOA precursors and reactive halogen species (RHS) at very low ozone concentrations allows the formation of halogen-induced organic aerosol, so-called XOA, in maritime areas where high concentrations of RHS are present, especially at sunrise. The present study combines aerosol smog-chamber and aerosol flow-reactor experiments for the characterization of XOA. XOA formation yields from alpha-pinene at low and high concentrations of chlorine as reactive halogen species (RHS) were determined using a 700 L aerosol smog-chamber with a solar simulator. The chemical transformation of the organic precursor during the aerosol formation process and chemical aging was studied using an aerosol flow-reactor coupled to an FTIR spectrometer. The FTIR dataset was analysed using 2D correlation spectroscopy. Chlorine induced homogeneous XOA formation takes place at even 2.5 ppb of molecular chlorine, which was photolysed by the solar simulator. The chemical pathway of XOA formation is characterized by the addition of chlorine and abstraction of hydrogen atoms, causing simultaneous carbon-chlorine bond formation. During further steps of the formation process, carboxylic acids are formed, which cause a SOA-like appearance of XOA. During the ozone-free formation of secondary organic aerosol with RHS a special kind of particulate matter (XOA) is formed, which is afterwards transformed to SOA by atmospheric aging or degradation pathways.