Ultrahigh-resolution FT-ICR mass spectrometry characterization of α-pinene ozonolysis SOA
Ultrahigh-resolution FT-ICR mass spectrometry characterization of α-pinene ozonolysis SOA
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DOI：
10.1016/j.atmosenv.2011.10.003
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发表时间：
2012
影响因子：
5
通讯作者：
A. Putman;J. Offenberg;R. Fisseha;S. Kundu;T. Rahn;L. Mazzoleni
中科院分区：
文献类型：
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作者：
A. Putman;J. Offenberg;R. Fisseha;S. Kundu;T. Rahn;L. Mazzoleni
采用超高分辨率傅里叶变换离子回旋共振质谱仪(FT-ICRMS)对α-蒎烯臭氧化反应中的二次有机气溶胶进行了表征。在100-850u的质量范围内，确定了900多个负离子的分子式。在α的臭氧分解过程中形成的羟基自由基可能会改变soa的组成，然而，在所有三个实验中都确定了大多数分子式，除了少数例外，它们具有相似的相对丰度。因此，清除羟基自由基正己烷的存在或不存在对SOA的详细组成只有轻微的影响。其负离子质谱图包含四组峰，随着相对分子质量的增加，峰的质量复杂性逐渐增大。随着相对分子质量的增加，O：C的平均值从0.55下降到0.42，而H：C的平均值约为1.5，不随相对分子质量的增加而变化。基团I和II中相对丰度最高的分子式分别含有5-7和7-10个氧原子以及3-4和5-7个双键当量。相对丰度最高的分子式分别含有10-13和13-16个氧原子和7-9和9-11个双键当量。对SOA产物的氧含量和双键当量的观察表明，这是一种复杂的堆积反应机制的混合，没有一条容易证实的主导途径。
Secondary organic aerosol (SOA) of α-pinene ozonolysis with and without hydroxyl radical scavenging hexane was characterized by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Molecular formulas for more than 900 negative ions were identified over the mass range of 100–850u. Hydroxyl radicals formed during the ozonolysis of α-pinene might be expected to alter the composition of SOA, however a majority of the molecular formulas were identified in all three experiments and with a few exceptions they had similar relative abundances. Thus, the detailed composition of SOA was only slightly influenced by the presence or absence of hydroxyl radical scavenging hexane. The negative-ion mass spectra of the SOA contained four groups of peaks with increasing mass spectral complexity corresponding to increasing molecular weight. The mean values of O:C decreased from 0.55 to 0.42 with increasing molecular weight, but the mean value of H:C, approximately 1.5, did not change with increasing molecular weight. The molecular formulas with the highest relative abundances in Groups I and II contained 5–7 and 7–10 oxygen atoms and 3–4 and 5–7 double bond equivalents, respectively. The molecular formulas with the highest relative abundances in Groups III and IV contained 10–13 and 13–16 oxygen atoms and 7–9 and 9–11 double bond equivalents, respectively. Observations of the oxygen content and the double bond equivalents of the SOA products suggest a complex mixture of accretion reaction mechanisms, without an easily confirmable dominating pathway.