Transitions from functionalization to fragmentation reactions of laboratory secondary organic aerosol (SOA) generated from the OH oxidation of alkane precursors.
Transitions from functionalization to fragmentation reactions of laboratory secondary organic aerosol (SOA) generated from the OH oxidation of alkane precursors.
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DOI：
10.1021/es300274t
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发表时间：
2012-05
影响因子：
11.4
通讯作者：
A. Lambe;T. Onasch;D. R. Croasdale;J. Wright;Alexander T Martin;J. Franklin;P. Massoli;J. Kroll;M. Canagaratna;W. Brune;D. Worsnop;P. Davidovits
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文献类型：
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作者：
A. Lambe;T. Onasch;D. R. Croasdale;J. Wright;Alexander T Martin;J. Franklin;P. Massoli;J. Kroll;M. Canagaratna;W. Brune;D. Worsnop;P. Davidovits
在无NO(x)的流动反应器中，研究了烷烃前驱体OH氧化形成二次有机气溶胶（SOA）的官能化（氧加成）和碎片化（碳损失）反应。SOA前驱体为正癸烷（n-C10）、正戊烷（n-C15）、正十七烷（n-C17）、三环[5.2.1.0(2,6)]癸烷（JP-10）以及柴油和南路易斯安那原油蒸气。使用高分辨率飞行时间气溶胶质谱仪测量气溶胶质谱，从中提取标准化SOA产率、氢碳比（H/C）和氧碳比（O/C），以及C(x)H(y)+、C(x)H(y)O+和C(x)H(y)O(2)+离子丰度作为OH暴露的函数。标准化的SOA产率曲线呈现出先上升后下降的特征，其最大产率在O/C比值范围为0.29至0.74之间。SOA产率的下降与氧含量的增加和碳含量的减少相关，与从功能化到碎片化的转变一致。对于一部分烷烃前体（n-C10、n-C15和JP-10）， SOA产率的最大值估计为0.39、0.69和1.1。此外，最大SOA产量对应于C(x)H(y)O+相对丰度的最大值。测量OH暴露、O/C比率和H/C比率之间的相关性，可以识别烷烃前体对环境SOA的贡献。
Functionalization (oxygen addition) and fragmentation (carbon loss) reactions governing secondary organic aerosol (SOA) formation from the OH oxidation of alkane precursors were studied in a flow reactor in the absence of NO(x). SOA precursors were n-decane (n-C10), n-pentadecane (n-C15), n-heptadecane (n-C17), tricyclo[5.2.1.0(2,6)]decane (JP-10), and vapors of diesel fuel and Southern Louisiana crude oil. Aerosol mass spectra were measured with a high-resolution time-of-flight aerosol mass spectrometer, from which normalized SOA yields, hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C) ratios, and C(x)H(y)+, C(x)H(y)O+, and C(x)H(y)O(2)+ ion abundances were extracted as a function of OH exposure. Normalized SOA yield curves exhibited an increase followed by a decrease as a function of OH exposure, with maximum yields at O/C ratios ranging from 0.29 to 0.74. The decrease in SOA yield correlates with an increase in oxygen content and decrease in carbon content, consistent with transitions from functionalization to fragmentation. For a subset of alkane precursors (n-C10, n-C15, and JP-10), maximum SOA yields were estimated to be 0.39, 0.69, and 1.1. In addition, maximum SOA yields correspond with a maximum in the C(x)H(y)O+ relative abundance. Measured correlations between OH exposure, O/C ratio, and H/C ratio may enable identification of alkane precursor contributions to ambient SOA.