RUI: Tropospheric Ozone and Aerosol Precursors from the Oxidation of Aromatics

在这个项目中，研究者将研究大气中丰富的芳香族化合物的氧化机制。实验将包括鉴定氧化系统中间体和稳定的最终产物，并通过湍流化学电离质谱（TF-CIMS）技术测量相关的动力学参数。特别是，CIMS方法将允许对反应系统种类进行更完整的识别，而TF方法将提供单独控制系统中OH和NOx水平的设施，以及执行与整个对流层相关的温度依赖性研究的能力。大气中芳香族化合物的氧化在对流层臭氧生成和二次有机气溶胶（SOA）形成等大气污染问题中起着重要作用。与大多数碳氢化合物一样，芳香族化合物的氧化产生过氧自由基，促进NO向NO2的转化，从而控制区域范围内臭氧的产生。此外，这些氧化过程会产生相对较大和较小但高度氧化的物质，这些物质很容易形成SOA。然而，最近的研究表明，我们目前对芳香族氧化机制的理解是严重错误的，因为这些模型在模拟大气条件的实验中明显高估了臭氧而低估了OH自由基的形成。还不清楚在大气中操作的顺序氧化过程中SOA前体是在什么时候形成的。这种情况对大气模式模拟和预测芳香族化合物对空气质量影响的能力产生了重大的负面影响。该项目的一个主要目标是通过对导致空气污染的过程的机械理解，为改善空气质量作出贡献。对芳香族化合物形成臭氧和气溶胶的化学过程的基本理解，有助于为公共政策过程提供信息，并有助于更迅速、更经济地解决空气污染问题。该计划还有一个更广泛的目标，即进一步发展国家科学事业所需的人力资源。特别是，在大气化学方面进行原创性研究的经验（对四年制院校的学生来说，这仍然是一个相当难得的机会）将吸引学生，并帮助他们为未来在大气科学领域的职业生涯做好准备。该计划还将有助于扩大和丰富奥柏林学院以及化学和生物化学系的知识氛围。

In this project, the Investigator will study the oxidation mechanisms of atmospherically abundant aromatic compounds. The experiments will include the identification of oxidation system intermediates and stable final products and the measurement of the relevant kinetic parameters via the turbulent flow chemical ionization mass spectrometry (TF-CIMS) technique. In particular, the CIMS approach will allow for a more complete identification of the reaction system species, and the TF method will provide the facility to separately control OH and NOx levels in the system as well as the ability to perform temperature dependence studies of relevance to the entire troposphere. The atmospheric oxidation of aromatic compounds plays a significant role in the air pollution problems of tropospheric ozone production and secondary organic aerosol (SOA) formation. Like most hydrocarbons, the oxidation of aromatic compounds produces peroxy radicals, which promote the NO to NO2 conversion that often controls ozone production on the regional scale. In addition, these oxidation processes lead to both relatively large and smaller, but highly oxidized, species that readily form SOA. However, recent studies have shown that our current understanding of the aromatic oxidation mechanism is significantly in error, as these models significantly overpredict ozone and underpredict OH radical formation in experiments in which atmospheric conditions are simulated. It is also unclear at what point SOA precursors are formed in the sequential oxidation process operative in the atmosphere. This situation has significant negative implications concerning the ability of atmospheric models to model and predict the impact of aromatic compounds on air quality. A major goal of the project is to contribute to the effort to improve air quality through a mechanistic understanding of the processes that lead to air pollution. The construction of a fundamental understanding of the chemistry that leads to ozone and aerosol formation for aromatic compounds serves to inform the public policy process and to contribute to a more expeditious and cost-effective solution to the problem of air pollution. This program also has the broader goal of furthering the development of the human resources necessary for the nation's scientific enterprise. In particular, the experience of performing original research in atmospheric chemistry (which is still a quite rare opportunity for students at four year institutions) will attract students and help prepare them for future careers in atmospheric science. The program will also serve to broaden and enrich the intellectual atmosphere at Oberlin College, and within the chemistry and biochemistry department.