Kinetic Studies of Isoprene Derived Peroxy Radicals

有机化合物异戊二烯是一种极其重要的自然排放物，在区域和全球范围内对对流层的化学成分做出了贡献。 光化学降解的细节已经研究了一段时间，但仍然存在差距，我们的理解率系数和机制的具体过程中，特别是在低氮氧化物（NOx）浓度的条件下。 这项研究将把两个机构（纽约州立大学环境科学与林业学院和密西西比州立大学）的专业知识结合起来，（1）产生特定的异戊二烯衍生的过氧自由基（RO 2），（2）基于近红外光谱区的腔衰荡光谱（CRDS）的新检测方法。 该项目的任务是产生过氧自由基，这些过氧自由基是由羟基自由基（OH）攻击异戊二烯产生的，将光谱分配给特定的异构体，并确定吸收截面。 然后，这些过氧自由基与NO（一氧化氮），HO 2（过氧化氢自由基），以及自由基自身反应的速率系数，将被量化。 根据这些动力学数据，将评估各种产物通道的分支比。 此外，详细的量子化学计算结果将与实验结果进行比较，以建立预测性的结构-活性关系，这项研究的结果将导致改进异戊二烯在大气中降解的化学机制，从而改进各种复杂程度的化学传输模型。 相关化合物（例如1，3-丁二烯、2-甲基-丁-3-烯-2-醇和萜烯）的化学性质也将通过本研究的结果得到更好的理解。 考虑到这些物种共同对全球大气的氧化能力有着极大的影响，因此全球大气的氧化能力将得到更好的限制。简而言之，这项工作将提高对异戊二烯和相关物种的大气化学的理解。 教育方面是重要的，因为一名研究生，一名博士后研究员和几名本科生将在激光光谱学，动力学，大气和量子力学建模以及生物圈-大气相互作用领域接受培训。 此外，还将促进调查机构（纽约州立大学环境科学和林业学院和密西西比州立大学）之间的合作。

The organic compound, isoprene, is an extremely important, naturally emitted species that contributes to the chemistry of the troposphere on regional and global scales. The details of the photochemical degradation have been studied for some time, but there remain gaps in our understanding of rate coefficients and mechanisms of specific processes, particularly under conditions of low oxides of nitrogen (NOx) concentrations. This study will link expertise at two institutions (State University of New York College of Environmental Science and Forestry, and Mississippi State University) in (1) producing specific isoprene derived peroxy radicals (RO2) with (2) new detection methods based on cavity ring down spectroscopy (CRDS) in the near infrared spectral region. The tasks of this project are to produce peroxy radicals that are generated from the attack of hydroxyl radicals (OH) on isoprene, assign spectra to particular isomers, and determine absorption cross sections. Then rate coefficients for the reactions of these peroxy radicals with NO (nitric oxide), HO2 (hydroperoxyl radicals), as well as the radical self reaction, will be quantified. From these kinetic data, branching ratios to various product channels will be assessed. In addition, results of detailed quantum chemical calculations will be compared with the experimental results in order to develop predictive structure-activity relationships.The results of this research will lead to improved chemical mechanisms for isoprene degradation in the atmosphere, thereby improving chemical transport models of various degrees of sophistication. The chemistry of related compounds (e.g. 1,3-butadiene, 2-methyl-but-3-en-2-ol, and terpenes) will also be better understood through results of this research. The oxidizing capacity of the global atmosphere will thus be better constrained, given that these species together have an extremely large influence on it. In short, this work will improve understanding of the atmospheric chemistry of isoprene and related species. The educational aspects are significant, since a graduate student, a postdoctoral fellow, and several undergraduate students will be trained in areas of laser spectroscopy, kinetics, atmospheric and quantum mechanical modeling, and biosphere-atmosphere interactions. In addition, collaboration between the investigator's institutions (SUNY College of Environmental Science and Forestry, and Mississippi State University) will be fostered.