Experimental and Theoretical Studies of Fundamental and Photochemical Processes in Aqueous Environments

美国国家科学基金会化学部的环境化学科学项目支持科罗拉多大学博尔德分校 Veronica Vaida 和 Rex T. Skodje 教授的研究，他们的团队进行了实验/理论合作，重点研究有机分子在空气/水界面和气相中的小水合簇中发生的光化学反应。这些光化学反应在大气气溶胶的形成和化学演化中发挥重要作用，对人类健康和气候变化具有潜在的重要影响。 拟议研究的智力价值源于解决阳光引发的、水介导的有机分子化学的基本科学问题。通过结合实验室和理论研究，这项工作的结果将是更好地理解在大气中重要的团簇和气溶胶表面发生的光化学反应的机制、动力学和速率。这项工作与其他工作的区别在于强调导出水环境中大气光化学的分子水平机制和定量模型。预计对气溶胶和更一般的水环境中发生的光化学所涉及的基础化学有更深入的了解。该工作的一个重要部分是使用法国 CESAM 仪器（实验多相大气模拟室）直接观察空气/水/有机气相混合物的光化学。在该室中进行的实验可以直接观察在强烈的紫外线/可见辐射的影响下气溶胶的形成和混合物的化学演化。就更广泛的影响而言，提高模拟气候变化所涉及的大气过程的能力是社会的一个重要目标，并且可以影响公共政策。当前模型中气溶胶的处理是一个“薄弱环节”，需要高度重视。 所提出的涉及气溶胶成核和化学演化的光化学机制的研究有可能通过对二次有机气溶胶的化学进行更正确的处理来提高这些模型的性能。此外，所提出的跨学科、国际合作将促进学生和博士后的交流，并促进不同机构之间在大气光化学基础科学方面的思想交叉。拟议的研究计划通过接触协作和跨学科的研究环境，有助于研究生和本科生的招募、保留和教育发展，特别是来自代表性不足的群体。

The Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation supports the research of Professors Veronica Vaida and Rex T. Skodje both at the University Colorado at Boulder in a collaborative experimental/theoretical effort by their groups that is focused on the study the photochemical reactions of organic molecules occurring at air/water interfaces and in small hydrated clusters in the gas phase. These photochemical reactions can play an important role in the formation and chemical evolution of atmospheric aerosols with potential important consequences to human health and climate change. The intellectual merit in the proposed investigation stems from addressing the basic scientific aspects of sunlight-initiated, water-mediated chemistry of organic molecules. Using a combination of laboratory and theoretical studies, the outcome of the work will be an improved understanding of the mechanisms, dynamics, and rates of photochemical reactions occurring in clusters and on aerosol surfaces that are of importance in the atmosphere. What distinguishes this work from other efforts is the emphasis on deriving molecular-level mechanisms and quantitative models for atmospheric photochemistry in aqueous environments. It is anticipated that greater understanding of the fundamental chemistry involved in the photochemistry occurring in aerosols and more general aqueous environments. An important part of the proposed work is the direct observation of the photochemistry of air/water/organic gas phase mixtures using the French CESAM instrument (Experimental Multiphasic Atmospheric Simulation Chamber). Experiments conducted in this chamber permit the direct observation of aerosol formation and the chemical evolution of the mixture under the influence of intense UV/visible radiation.In terms of broader impacts, improving the ability to model atmospheric processes involved in climate change is an important goal for society and can impact public policy. The treatment of aerosols in current models is a "weak link" and requires significant attention. The proposed study of photochemical mechanisms involved in aerosol nucleation and chemical evolution has the potential to provide improved performance of these models by incorporating a more correct treatment of the chemistry of secondary organic aerosols. In addition, the interdisciplinary, international collaborations proposed will lead to the exchange of students and postdoctoral fellows, and promote cross-fertilization of ideas between different institutions in the basic science of atmospheric photochemistry. The proposed research program contributes to the recruitment, retention and educational development of graduate and undergraduate students, especially from under-represented groups, by exposure to a collaborative and interdisciplinary research environment.