实时监测质谱中典型VOCs和离子及水合团簇反应机理和动力学

挥发性有机化合物(VOCs)是大气臭氧和PM2.5形成的重要前体物。VOCs实时监测质谱因灵敏度高、响应时间短，且无须浓缩和分离，成为目前大气VOCs最重要的在线监测手段。VOCs带电是实现质谱监测的必要前提。此过程依赖于VOCs和离子源产生的离子反应带电，形成碎片离子束，并在质量分析器电磁场中实现质荷比(m/z)的分离。本项目拟采用量子化学计算和从头算分子动力学模拟的方法，结合适当的质谱实验验证，系统地研究实时监测质谱中典型VOCs和H3O+、NO+和O2+的分子-离子反应及后续裂解、重排和异构化反应的详细机理，重点阐明水分子和团簇对反应机理的影响。构建VOCs电子结构和速率常数QSAR模型，分析结构特征对反应机理和活性的影响。本项目可为全面评价VOCs在实时监测质谱中的反应活性和响应时间，更精准地在线监测和污染控制提供理论依据，同时可为质谱研发者提高质谱性能、丰富质谱库提供数据支撑。

Volatile organic compounds (VOCs) are important precursors in the formations of atmospheric ozone and PM2.5. Real-time and accurate monitoring of VOCs is conducive to understand the contributive factor of air pollution and continuously improve of regional air quality. Due to the high sensitivity, short response time and no detection without concentration and separation, real-time monitoring mass spectrometry has become the most important method for on-line detecting of VOCs in the atmosphere. The process of making VOCs charged is a necessary prerequisite for mass spectrometry monitoring, which relies on the molecular-ion reaction between VOCs and the ions generated by the ion source to form a fragment ion beam. The ion beam will be separated according to the mass-to-charge ratio (m/z) in the electromagnetic field of the mass analyzer. This project intends to employ quantum chemistry calculations and ab initio molecular dynamics simulation methods, combining with appropriate mass spectrometry experimental verification, to systematically study the molecular-ion reaction mechanisms of typical VOCs with H3O+, NO+ and O2+ in real-time monitoring of mass spectrometry and the subsequent cracking, rearrangement and isomerization reactions of the ion fragments. The highlights word of this project is to clarity the effects of water molecules and clusters on the reaction mechanism. By constructing the QSAR models of electronic structures and rate constants, the influence of VOCs structure characteristics on reaction mechanism and reactivity can be analyzed. This project can provide a theoretical basis for comprehensively evaluating the reactivity and response time of VOCs in real-time monitoring mass spectrometry and precisely controlling pollution and online monitoring of VOCs, as well as supply data support for mass spectrometer developers to improve their performance and enrich the mass spectrometer library.