Kinetics of the Hydroxyl Radical (OH) and Ozone-Initiated Oxidation of Biogenic Terpenes

该项目的总体目标是通过研究异戊二烯和各种萜烯（如法呢烯、4，8-二甲基-1，3，7-壬三烯、β-月桂烯和β-罗勒烯）的OH（羟基自由基）和臭氧引发氧化的动力学和机制，更好地了解生物排放对大气化学的影响。 这些生物源挥发性有机化合物（BVOCs）最近已被确定在森林中，可能是部分负责非常快速的化学反应与大气中的氧化剂在这些环境中。 实验将包括这些化合物与OH和臭氧的反应速率常数的测量，这些化合物的臭氧分解产生的OH自由基的产率的直接测量，以及一些产品的鉴定和定量。 实验将使用在线质谱与相对速率技术，以及放电流技术与激光诱导荧光检测的OH。 这项研究应该会加深对一些氧化机制细节的了解，并将有助于确定这些BVOC在产生光化学烟雾中的效率。 测量还将有助于确定生物排放是否是白天和晚上OH自由基的重要来源，该项目的结果将对理解生物排放对大气中臭氧和气溶胶形成的贡献产生更广泛的影响。 该项目还将为研究生和本科生，包括代表性不足人口的几名学生提供研究和教育机会。

The overall goal of this project is an improved understanding of the influence of biogenic emissions on atmospheric chemistry, through studies of the kinetics and mechanisms of the OH (hydroxyl radical) and ozone-initiated oxidation of isoprene and various terpenes, such as farnesenes, 4,8-dimethyl-1,3,7-nonatriene (DMNT), beta-myrcene, and beta-ocimene. These biogenic volatile organic compounds (BVOCs) have recently been identified in forests, and may be partially responsible for very rapid chemical reactions with atmospheric oxidants in these environments. Experiments will include measurements of rate constants for the reactions of these compounds with OH and ozone, direct measurements of the yield of OH radicals produced by ozonolysis of these compounds, and identification and quantification of some of the products. The experiments will use on-line mass spectrometry with relative rate techniques as well as discharge flow techniques with laser-induced fluorescence detection of OH. This study should lead to improved knowledge of the details of some of the oxidation mechanisms and will help to determine the efficiency of these BVOCs in the production of photochemical smog. The measurements will also help to determine whether biogenic emissions are a significant source of OH radicals both during the day and at night.The results of this project will have broader impacts on understanding the contribution of biogenic emissions to ozone and aerosol formation in the atmosphere. This project will also provide research and educational opportunities for graduate students and undergraduates, including several students from under-represented populations.