Photochemistry at Organic Particle-Air Interfaces

在该项目下开展的研究将研究大气中颗粒的气固界面上发生的光化学过程的基本机制；具体地说，那些控制被臭氧和/或羟基自由基部分氧化的有机薄膜的紫外光分解的机制。要使用的主要技术是红外“腔衰荡光谱”，以检测从辐照表面析出的气相产物。第二个目标是研究不饱和有机物的臭氧分解。这项研究的结果将适用于在地球大气中发挥关键作用的气溶胶粒子，从为化学反应提供独特的异质环境到作为云形成的凝结核和有效地散射太阳辐射。由于气溶胶粒子在白天持续暴露在太阳辐射下，它们有可能成为大气中光化学过程的介质，或者在特殊情况下作为催化剂。这一研究将有助于建立合理的低层大气颗粒物环境标准，并提高空气污染和全球气候模式的预测能力。了解气溶胶颗粒的光化学性质将有助于更好地预测它们的大气命运和环境影响，并最终减少人口接触特别有害的气溶胶的风险。这项工作包括为一年级学生开设一门关于空气污染的课程，使用调查员的实验室仪器培训研究生和本科生，为高中理科教师提供实践培训，以及向公众举办教育研讨会。

The research performed under this project will investigate the mechanisms underlying photochemical processes that occur on the air-solid interfaces of particles in the atmosphere; specifically, those governing the ultraviolet photolysis of organic films that have been partially oxidized by ozone and/or the hydroxyl radical. The principal technique to be used is infrared "cavity ring-down spectroscopy" to detect gas-phase products evolved from the irradiated surfaces. A secondary goal is to study the ozonolysis of unsaturated organics. The results of this research will be applicable to aerosol particles which play a pivotal role in the Earth's atmosphere, from providing a unique heterogeneous environment for chemical reactions to serving as condensation nuclei for cloud formation and efficiently scattering solar radiation. Because aerosol particles are continuously exposed to solar radiation during the daytime, they can potentially serve as media or, in special cases, as catalysts for photochemical processes in the atmosphere.This research will be useful for establishing rational environmental standards for particulate matter in the lower atmosphere, and for improving the predictive power of air pollution and global climate models. Understanding photochemical properties of aerosol particles will help to better predict their atmospheric fates and environmental impacts, and ultimately reduce the risk of population exposure to especially harmful aerosols. This work includes creating a course on air pollution for freshman students, and using the investigator's laboratory instrumentation for training graduate and undergraduate students, providing hands-on training for high school science teachers, and presenting educational seminars to the general public.