Multiphase Reactivity of Atmospheric Organic Radicals: Gas- vs. Liquid- vs. Particle-phase Chemistry

该奖项得到化学部环境化学科学计划的支持。杰西·克罗尔教授和威廉·格林教授以及他们的研究生和本科生研究大气中高活性物质（称为自由基）与有机化合物的反应。许多对人类健康、生态健康和气候至关重要的环境化学过程是通过有机化合物的氧化发生的。这包括控制空气和水污染物水平的化学反应。反应机理可能极其复杂，涉及大量化学中间体和产物。形成高反应性自由基中间体、有机过氧自由基(RO2)和烷氧基自由基(RO)。这些自由基可以通过多种途径发生反应，并形成多种产物。该项目旨在提高我们对这些反应的速率和产物的理解。重点是反应条件如何控制这种反应性。这种理解最终可以改进各种重要环境过程的模型。这可以实现更好的预测并最终做出更明智的政策决策。该项目涉及各种环境条件下 RO 和 RO2 自由基反应性的实验（实验室）和计算（建模）研究。 在实验中，自由基是通过适当的前体分子的光解产生的。这是在气相（使用流动反应器）、本体液相（使用液体间歇反应器）和亚微米气溶胶颗粒内（在气溶胶流动管中）完成的。产品主要通过两种仪器进行检测：用于凝相产品的气溶胶质谱仪和用于气态产品的化学电离质谱仪。实验室研究与建模工作同时进行。这将速率和产品分布与详细的化学机制联系起来。计算工具包括结构和能量的量子化学计算、反应速率计算以及使用反应机制生成器对复杂反应机制进行化学动力学建模。

This award is supported by the Chemistry Division's Environmental Chemical Sciences Program. Prof. Jesse Kroll and William Green and their graduate and undergraduate students study the reactions of highly reactive species in the atmosphere, called radicals, with organic compounds. Many environmental chemical processes central to human health, ecological health, and climate occur via the oxidation of organic compounds. This includes the chemical reactions that control the levels of air and water pollutants. The reaction mechanisms can be extremely complex, involving a large of number of chemical intermediates and products. Highly reactive radical intermediates, organic peroxy radicals (RO2) and alkoxy radicals (RO), are formed. These radicals can react via a number of channels, and form a wide range of products. This project aims to improve our understanding of the rates and the products of these reactions. The focus is on how the reaction conditions may control such reactivity. This understanding can ultimately lead to improved models of a wide range of important environmental processes. This enables better predictions and ultimately more informed policy decisions. This project involves both experimental (laboratory) and computational (modeling) studies of RO and RO2 radical reactivity under a wide range of environmental conditions. In the experiments, the radicals are generated by photolysis of appropriate precursor molecules. This is done in the gas phase (using a flow reactor), the bulk liquid phase (using a liquid batch reactor), and within submicron aerosol particles (in an aerosol flow tube). Products are detected primarily by two instruments, an aerosol mass spectrometer for the condensed-phase products and a chemical ionization mass spectrometer for the gaseous products. The laboratory studies are carried out in parallel with the modeling work. This links rates and product distributions with detailed chemical mechanisms. Computational tools include quantum-chemical calculations of structures and energies, calculations of reaction rates, and chemical kinetic modeling of complex reaction mechanisms using the Reaction Mechanism Generator.