RUI: Overall Rate Constant and Nitrate Branching Ratio Measurements for the Reactions of Alkene-Derived Peroxy Radicals with Nitric Oxide

臭氧形成和破坏的对流层化学取决于许多因素。其中一个关键的气相化学反应是过氧化氢和有机过氧化氢自由基氧化一氧化氮。对于羟基和较小的有机过氧自由基，反应几乎完全通过一氧化氮转化为二氧化氮并形成烷氧基自由基来进行。后者通常与氧反应形成羟基自由基。更大更复杂的多取代有机过氧基表现出第二反应途径，导致有机硝酸盐的形成。对于一些简单的直链烷基过氧自由基，已经研究了第二反应通道的速率系数，但对于更复杂的自由基，如羟基自由基与烯烃（含双键的碳氢化合物）反应产生的自由基，数据很少且不一致。本研究系统地考察了有机过氧自由基与一氧化氮的反应动力学和生成有机硝酸盐的分支比率，这些有机硝酸盐来源于一些含有2到5个碳原子的烯烃。羟基自由基与烯烃反应产生的过氧自由基称为-羟基过氧自由基，研究相对较少。紊流化学电离质谱技术将用于控制实验条件和定量反应产物的产率。研究将作为温度的函数进行。这些数据将对大气化学建模非常有用，但也可以用来建立结构-反应性关系，从而可以预测其他未测量物种的产量。本研究将在一所本科院校进行，并在项目中大量利用本科生研究助理。

The tropospheric chemistry of ozone formation and destruction depends on many factors. One of the key gas-phase chemical reactions is the oxidation of nitric oxide by hydroperoxyl and organic peroxyl radicals. For hydroperoxyl and smaller organic peroxyl radicals, the reactions proceed almost exclusively by conversion of nitric oxide to nitrogen dioxide accompanied by formation of alkoxy radicals. The latter usually react with oxygen to form hydroperoxyl radicals. Larger and more complex, multiply substituted organic peroxyl radicals exhibit a second reaction pathway, leading to the formation of organic nitrates. The rate coefficients for this second reaction channel have been studied for some simple, straight-chained alkylperoxy radicals, but data are sparse and inconsistent for more complex radicals, such as those derived from the reaction of hydroxyl radicals with alkenes (double bond containing hydrocarbons). This study involves the systematic examination of the organic peroxyl radical plus nitric oxide reaction kinetics and branching ratios to form organic nitrates for radicals derived from a number of alkenes containing two to five carbon atoms. The peroxy radicals derived from hydroxyl radical-alkene reactions are called beta-hydroxy peroxy radicals, and have been studied relatively little. The technique of turbulent flow chemical ionization mass spectroscopy will be used to control the experimental conditions and quantify the yields of reaction products. Studies will be performed as a function of temperature. These data will be extremely useful for atmospheric chemical modeling, but can also be used to build structure-reactivity relationships that may allow prediction of yields from other, unmeasured species.This research will be carried out at an undergraduate institution with significant utilization of undergraduate research assistants in the project.