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类，如法尼烯、4，8-二甲基-1，3，7-二十三烯(DMNT)、β-月桂烯和β-罗勒烯的羟基和臭氧氧化的动力学和机理，更好地了解生物排放对大气化学的影响。这些生物来源的挥发性有机化合物(BVOC)最近在森林中被发现，可能是在这些环境中与大气氧化剂发生非常快速的化学反应的部分原因。实验将包括测量这些化合物与OH和臭氧反应的速率常数，直接测量这些化合物通过臭氧氧化产生的OH自由基的产率，以及对一些产品进行鉴定和定量。这些实验将使用在线质谱仪和相对速率技术，以及放电流动技术和激光诱导荧光检测OH。这项研究应有助于更好地了解某些氧化机制的细节，并将有助于确定这些BVOCs在产生光化学烟雾方面的效率。这些测量还将有助于确定生物排放是否在白天和夜间都是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提供研究和教育机会，包括来自代表性不足人口的几名学生。

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.