Measurements of secondary organic aerosol from oxidation of cycloalkenes, terpenes, and m-xylene using an Aerodyne aerosol mass spectrometer
Measurements of secondary organic aerosol from oxidation of cycloalkenes, terpenes, and m-xylene using an Aerodyne aerosol mass spectrometer
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DOI：
10.1021/es048061a
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发表时间：
2005-08-01
影响因子：
11.4
通讯作者：
Jimenez, JL
中科院分区：
文献类型：
--
作者：
Bahreini, R;Keywood, MD;Jimenez, JL
利用Aerodyne气溶胶质谱仪(AMS)表征了环烯烃臭氧氧化和间二甲苯光氧化生成的二次有机气溶胶的物理化学性质。通过对AMS和差示迁移率分析仪的质量和体积分布进行比较，根据具体系统的不同，可以估计出SOA的“有效”密度在0.64-1.45g/cm(3)之间。在环烯烃成核实验中，m/z 44处的碎片、含氧有机物的Co2+离子碎片和较高的“Delta”值在环烯烃成核实验中的贡献增加，表明与种子实验中形成的分子相比，更多的含氧分子对SOA的贡献更大。在生物质臭氧分解过程中形成的优势负值的“Delta”值表明，在SOA中存在萜类衍生物结构或环状或不饱和含氧化合物。在α-蒎烯的臭氧化反应中，观察到了酸催化的多相化学的证据，其特征是较高分子量的碎片对SOA的贡献更大，并且相应地改变了“Delta”模式。间二甲苯光氧化过程中形成的SOA质谱特征与呋喃二酮类化合物和硝基有机物的存在相一致。这项研究表明，由类似的前体产生的SOA化合物的混合物产生了非常相似的AMS质谱图。因此，观察到的生物来源与人为来源的碎片模式在确定环境中的来源方面可能是有用的。
The Aerodyne aerosol mass spectrometer (AMS) was used to characterize physical and chemical properties of secondary organic aerosol (SOA) formed during ozonolysis of cycloalkenes and biogenic hydrocarbons and photo-oxidation of m-xylene. Comparison of mass and volume distributions from the AMS and differential mobility analyzers yielded estimates of "effective" density of the SOA in the range of 0.64-1.45 g/cm(3), depending on the particular system. Increased contribution of the fragment at m/z 44, CO2+ ion fragment of oxygenated organics, and higher "Delta" values, based on ion series analysis of the mass spectra, in nucleation experiments of cycloalkenes suggest greater contribution of more oxygenated molecules to the SOA as compared to those formed under seeded experiments. Dominant negative "Delta" values of SOA formed during ozonolysis of biogenics indicates the presence of terpene derivative structures or cyclic or unsaturated oxygenated compounds in the SOA. Evidence of acid-catalyzed heterogeneous chemistry, characterized by greater contribution of higher molecular weight fragments to the SOA and corresponding changes in "Delta" patterns, is observed in the ozonolysis of alpha-pinene. Mass spectra of SOA formed during photo-oxidation of m-xylene exhibit features consistent with the presence of furandione compounds and nitro organics. This study demonstrates that mixtures of SOA compounds produced from similar precursors result in broadly similar AMS mass spectra. Thus, fragmentation patterns observed for biogenic versus anthropogenic SOA may be useful in determining the sources of ambient SOA.