Reactions of Hydroxyl Radicals and Ozone with Volatile Organic Compounds Within Gas Phase Clusters: Experiment and Theory

羟基自由基（OH）与生物或人为来源的挥发性有机化合物（VOCs）的反应是对流层臭氧的主要来源。OH与VOCs的反应也会导致有害的酸性化合物的形成。VOCs与臭氧反应形成多种产物，包括高能双自由基和OH自由基，臭氧-烯烃反应可能是夜间OH的重要来源。本项目探讨了气溶胶粒子（雾、雨、云滴等）的存在如何介导上述反应。在这项研究中，它将确定如何气相化学变化，如果自由基反应发生在一个气相分子簇中，作为一个更大的空气气溶胶颗粒的模型。布法罗大学的研究小组在实验和理论上都有研究气相团簇化学反应的经验。我们经常观察到，在团簇中发生的化学反应与在气相中发生的化学反应大不相同。团簇内的分子溶剂化可以使试剂或中间体在足够长的时间尺度上稳定下来，以便在团簇内发生反应。在这些实验中，将通过分子束扩张制备含有硝酸、VOC、水和其他配体分子的气相团簇。氢氧根将通过硝酸或其他合适的前体光解产生。反应产物将通过串联质谱法监测。理论计算将提供中间双基的能量学和寿命的估计。

9713381 Garvey The reaction of hydroxyl radical (OH) with volatile organic compounds (VOCs) of biogenic or anthropogenic origin is a major source of tropospheric ozone. The reaction of OH with VOCs can also lead to the formation of harmful acidic compounds. VOCs react with ozone to form a variety of products, including energetic biradicals and OH radicals, and ozone-alkene reactions can be an important nighttime source of OH. This project addresses how the above reactions could be mediated by the presence of aerosol particles (fog, rain, cloud droplets, etc.). In this research, it will be determined how the gas phase chemistry changes if the radical reactions occur within a gas phase cluster of molecules as a model of much larger airborne aerosol particles. The University at Buffalo group has experience in studying chemical reactions within gas phase clusters both experimentally and theoretically. It was observed that frequently, the chemistry occurring in clusters is very different from that in the gas phase. Solvating molecules within the cluster can stabilize a reagent or intermediate on a time scale long enough to react within the cluster. In these experiments, gas phase clusters containing nitric acid, the VOC, water, and other ligand molecules will be prepared via molecular beam expansion. OH will be produced via photolysis of nitric acid or other suitable precursors. Reaction products will be monitored via tandem mass spectrometry. Theoretical calculations will provide estimates of the energetics and lifetimes of intermediate biradicals.