To further explore the composition and distribution of secondary organic aerosol (SOA) components from the photo-oxidation of light aromatic precursors (toluene, m-xylene, and 1,3,5-trimethylbenzene (1,3,5-TMB)) and idling gasoline exhaust, a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) was employed. Peaks of the molecular ions of the SOA components with minimum molecular fragmentation were clearly observed from the mass spectra of SOA, through the application of soft ionization methods in VUV-PIMS. The experiments comparing the exhaust-SOA and light aromatic mixture-SOA showed that the observed distributions of almost all the predominant cluster ions in the exhaust-SOA were similar to that of the mixture-SOA. Based on the characterization experiments of SOA formed from individual light aromatic precursors, the SOA components with molecular weights of 98 and 110 amu observed in the exhaust-SOA resulted from the photo-oxidation of toluene and m-xylene; the components with a molecular weight of 124 amu were derived mainly from m-xylene; and the components with molecular weights of 100, 112, 128, 138, and 156 amu were mainly derived from 1,3,5-TMB. These results suggest that C₇-C₉ light aromatic hydrocarbons are significant SOA precursors and that major SOA components originate from gasoline exhaust. Additionally, some new light aromatic hydrocarbon-SOA components were observed for the first time using VUV-PIMS. The corresponding reaction mechanisms were also proposed in this study to enrich the knowledge base of the formation mechanisms of light aromatic hydrocarbon-SOA compounds.

为了进一步探索从光芳族前体（甲苯，光氧化组合物和二次有机气溶胶（SOA）的组件的分布米-二甲苯和1,3,5-三甲基苯（1,3,5-TMB））和空转汽油废气，使用了真空紫外光电离质谱仪（VUV-PIMS）。通过在VUV-PIMS中应用软电离方法，从SOA质谱图中可以清楚地观察到具有最小分子碎片的SOA组分的分子离子峰。比较排气-SOA和轻质芳族混合物-SOA的实验表明，在排气-SOA中观察到的几乎所有主要的簇离子分布都与混合物-SOA相似。基于从各个光芳族前体形成SOA的表征实验，用在排气SOA观察到98和110原子质量单位的分子量的SOA组件导致从甲苯和的光氧化米-二甲苯; 用124原子质量单位的分子量的组分主要来源于米二甲苯; 分子量分别为100、112、128、138和156 amu的组分主要来自1,3,5-TMB。这些结果表明，C ₇ -C ₉轻质芳烃是重要的SOA前体，并且主要的SOA成分来自汽油废气。此外，使用VUV-PIMS首次观察到一些新的轻质芳烃SOA组分。本研究还提出了相应的反应机理，以丰富有关轻质芳烃-SOA化合物形成机理的知识基础。