同步辐射光电离质谱技术研究C3 Criegee中间体宏观反应动力学

项目名称： 同步辐射光电离质谱技术研究C3 Criegee中间体宏观反应动力学

项目编号： No.91544105

项目类型： 重大研究计划

立项/批准年度： 2016

项目学科： 天文学、地球科学

项目作者： 刘付轶

作者单位： 中国科学技术大学

项目金额： 86万元

中文摘要： 地球大气中的烃类与臭氧反应生成的羰基氧化物，即Criegee中间体(CI)，是冬天和夜间OH自由基的来源(非光反应产生)。它能与空气中许多分子反应，形成二次有机气溶胶。目前对较小C1、C2 CI的反应动力学研究比较充分，但直接测量的速率常数与以前数据相差很大，对大气模拟研究有较大影响；而对C3 CI [即(CH3)2COO、C2H5CHOO]的研究刚起步。利用已建立的流动管反应器和激光闪光光解产生C3 CI作为起始反应，从流动管侧孔取样，使用高亮度同步辐射单光子电离和飞行时间质谱仪探测反应产物，研究C3 CI与H2O、NO2、SO2等分子的反应动力学。实验直接测量其反应速率常数、时间分辨反应产物并区分其异构体；结合量化计算获得反应中间体、过渡态和势能面等，掌握其反应动力学机理，为准确模拟大气化学反应过程提供可靠的动力学数据。该实验研究拓展同步辐射应用领域，充分发挥国家大科学装置的作用。

中文关键词： Criegee中间体；反应动力学；激光闪光光解；同步辐射光电离；大气化学

英文摘要： Criegee intermediates (CIs), which are formed in the reactions of ozone with alkenes in the earth's atmosphere, are responsible for the non-photolytic productions of OH during winter and at night. CIs can react with many molecules in the atmosphere and form second organic aerosols (SOA). The reaction rate constants for C1 and C2 CIs are much faster than previous literature suggested and the atmospheric reaction models need to be adjusted, while the reactions for C3 CIs [(CH3)2COO, C2H5CHOO] are poor. C3 CIs are formed by laser flash photolysis in the flow reaction tube. Utilizing SR photoionization and reflectron time-of-flight mass spectrometer (RTOF MS) for product detection, the approach is capable of further research on kinetics for reactions of C3 CIs with H2O, NO2 and SO2. The experiments enable the direct measurements of rate coefficients, time-resolution detection of reaction products and distinguishing of different structural isomers. Combining with the reaction intermediates, transition states and potential energy surfaces from theoretical calculations, the reaction mechanisms will be unravelled comprehensively, and reliable kinetic data will be provided for accurate simulation of reaction progresses in the atmospheric chemistry. The experimental research extends the application fields of synchrotron radiation and will perform function as extension of national large-scale scientific research facilities.

英文关键词： Criegee internediate;Reaction kinetics;Laser flash photolysis;SR photoionization;Atmospheric chemistry