AGS-PRF: Peroxy Radical (RO2) Reactivity through Functionalized Organic Iodides

这个项目包括实验室实验，以更好地表征大气中过氧基的反应化学。过氧基是二次有机气溶胶和臭氧产生的关键中间体，对人体健康有害，对气候有影响。在实验室中将使用流动管来研究许多不同环境条件下的过氧自由基反应。本研究的目的是：(1)确定分子结构和官能化程度对过氧基(RO2)异构化速率和二聚化产物的影响；(2)确定官能化的RO2物种的有机硝酸盐产率和烷氧基的去向；(3)确定RO2-HO2反应中过氧化氢(RoOH)和羟基的分支比。第一个目标包括探测RO2单分子反应和RO2-RO2的反应性，并确定每个过程的相对重要性。第二个目标包括探测RO2-NO的反应性，并评估这些反应与目标1中描述的异构化反应之间的相对速率。第三个目标将有助于评估以下假设：在RO2-HO2反应中，OH的产率随着官能化程度的增加而增加。在清洁的环境中，双分子寿命很长，多个异构化反应可能导致RO2物种非常官能化，与HO2反应时更有可能产生OH，而不是形成过氧化物。这些实验结果将提供了解大气氧化所必需的RO2双分子反应的异构化速率和支化比的基本实验数据。这项研究的成功将改进氧化过程的模拟，在“高”和“低”NOx环境条件下，从而帮助改善对空气质量和气候变化的预测。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project involves laboratory experiments to better characterize the reactive chemistry of peroxy radicals in the atmosphere. Peroxy radicals are key intermediate species in the production of secondary organic aerosol and ozone, which are detrimental to human health and affect climate. A flow tube will be used in the laboratory to study peroxy radical reactions under many different environmental conditions. A better understanding of this chemistry has implications for modeling air quality and for informing policy decisions on mitigating air pollution levels that may be harmful to human health.The objectives of this research are: (1) to determine the effects of molecular structure and degree of functionalization on isomerization rates and dimerization products of peroxy radicals (RO2); (2) to determine the organic nitrate yield and alkoxy radical fate of functionalized RO2 species; and (3) to determine the branching ratio of hydroperoxides (ROOH) and OH in RO2-HO2 reactions where the RO2 radical is functionalized. The first objective involves probing RO2 unimolecular reactions and RO2-RO2 reactivity and determining the relative importance of each process. The second objective includes probing RO2-NO reactivity and evaluating the relative rates between these reactions and the isomerization reactions described in the Objective 1. The third objective will help to assess the hypothesis that the yield of OH increases as the degree of functionalization increases in RO2- HO2 reactions. In clean environments, where bimolecular lifetimes are long, multiple isomerization reactions might lead to RO2 species that are very functionalized and more likely to yield OH when reacting with HO2 than to form peroxides. The results from these experiments will provide fundamental experimental data on isomerization rates and branching ratios of bimolecular reactions of RO2 necessary to understand atmospheric oxidation. The success of this research will lead to the improved modeling of oxidation processes, under the conditions of both “high” and “low" NOx environments, thereby helping to improve predictions of both air quality and climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.