Criegee自由基大气化学反应机理与二次有机气溶胶形成

Criegee radicals RR'COO and organic peroxy radicals ROO, although not a primary component in atmosphere are highly active ingredients and an important participant for the atmospheric chemical pollution on the troposphere, which having a crucial impact on organic aerosols and photochemical smog formation, climate change and other environmental problem. The atmospheric reaction mechanism of Criegee radicals will be investigated systematically with quantum chemical calculations methods. The project aims at fundamental scientific issues, the proper method for the open-shell diradical, the law of multi-degree of PES for the favorable reaction channel, the reaction mechanism and water molecules catalysis the reaction. To the end, a high accurate and high efficient method will be established for the system with large open-shell diradicals using the combination of the broken symmetric theory and accurate methods MRCI and others. A basic law for the PES multi-degree of favorable reaction channel will be summarized. The Chemical reaction mechanism of Criegee radicals with typical species and the formation mechanism of atmospheric secondary organic aerosol ROO (CH2OO)nH will be revealed and the reaction mechanism and kinetics of atmospheric RR'COO will be investigated under the presence of water clusters. The results can be expected to provide theoretical guidance to eliminate atmospheric haze pollution to improve the atmospheric environment and other related applied research.

Criegee自由基RR'COO与有机过氧自由基ROO虽然不是地球大气的主要组成部分，但它们均是大气中的高活性成分，对光化学烟雾与有机气溶胶形成等环境问题有重要影响。本项目针对Criegee自由基大气化学反应研究中存在的双自由基计算方法选取、优势通道PES多重度规律确定、反应机理揭示、水分子如何催化等几个重要基本科学问题开展全面计算研究。基于对称性破损与多参考态相互作用等精确计算相结合方案，探索建立一种既有较高计算精度又有较高效率的适合于较大双自由基体系的组合计算方法；系统研究RR'COO低聚及与ROO, SO2, NO2等典型大气物种反应体系，并详细考察水分子存在对反应机理与动力学性质的影响；深入揭示自由基-自由基反应优势通道多重度规律、二次有机气溶胶ROO(CH2OO)nH形成及RR'COO自由基大气化学反应机理。本项目研究为消除大气雾霾污染、改善大气环境质量等相关应用研究提供理论指导

本项目按原计划书设定的研究目标执行，完成了全部预定目标。详细研究了CH2OO基态/激发态的电子结构、光解离行为、Criegee中间体异构化、双分子自反应、与大气小分子反应以及大气自由基-自由基等50多个反应体系，构建了不同多重度势能面，深入剖析了反应微观机理；总结了相关自由基-自由基反应优势通道的多重度规律；详细考察了水分子以不同模型存在时对反应机理与动力学性质的影响；推断提出了关于ROO(CH2OO)nH形成的新机理。项目执行期间研究成果先后在JPC Letter, PCCP, Atmos. Environ, ACS Appl. Mater Interfaces, Molecular Physics,Theor. Chem. Acc.等期刊发表SCI学术论文29篇，提交会议论文19篇，参加学术会议30余人次。培养博士研究生2人，博士后出站1人，毕业硕士研究生9人。本项目（21473108）部分研究成果与先前国家基金项目（20873079）成果获2017年陕西省科学技术二等奖（获奖项目名称：几类重要反应微观机理与动力学的理论研究）。