Effect of Condensed-Phase Photochemistry on Absorption Coefficients and Phase State of Atmospheric Organic Aerosol Particles

该项目的目标是更好地了解有机化合物的固液相光化学反应如何影响大气中有机气溶胶的关键特性。本项目的重点是二次有机气溶胶和/或生物质燃烧有机气溶胶。这项研究对改善大气有机粒子和含有溶解有机物的云滴内发生的光化学反应的建模具有重要意义。该项目的结果将增进对有机颗粒如何直接和间接地促进对气候的辐射强迫的理解，并为预测城市环境中老化的有机颗粒物质对健康的影响提供有价值的信息。本研究的主要目的是：(1)比较二次有机气溶胶（SOA）和生物质燃烧有机气溶胶（BBOA）化合物在不同基质下的光化学过程机制，这些基质分别代表云滴中的稀水环境、气溶胶液态水中的浓水环境和颗粒的有机相；(2)评估辐照SOA和BBOA中直接和间接光化学过程的相对重要性；(3)考察凝聚相光化学过程对SOA和BBOA材料的吸收系数、粘度和相行为的影响。该项目将通过在烟雾室或氧化流反应器中进行的实验来进行。这项工作将直接支持至少两名研究生和六名本科生的培训。该项目的结果将通过研究会议、同行评议出版物、互联网和公共媒体传播。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of this project is to better understand how photochemical reactions in the solid or liquid phase of organic compounds affect the key properties of organic aerosol in the atmosphere. The focus of this project is on secondary organic aerosol and/or biomass burning organic aerosol. This research is important to improve the modeling of photochemical reactions that occur inside atmospheric organic particles and cloud droplets containing dissolved organics. The results of this project will improve the understanding of how organic particles contribute to radiative forcing on climate both directly and indirectly and provide valuable information relevant to predicting the health effects of aged organic particulate matter in the urban environment.The main objectives of this proposal are to: (1) compare mechanisms of photochemical processes for secondary organic aerosol (SOA) and biomass burning organic aerosol (BBOA) compounds in different matrices representative of the dilute aqueous environment found in cloud droplets, the concentrated aqueous environment in aerosol liquid water, and the organic phase of particles; (2) assess the relative importance of direct and indirect photochemical processes in irradiated SOA and BBOA; and (3) examine the effect of condensed-phase photochemical processes on absorption coefficients, viscosity and the phase behavior of SOA and BBOA materials. The project will be conducted through experiments carried out in a smog chamber or an oxidation flow reactor.This effort will directly support the training of at least two graduate students and six undergraduate students. The results of this project will be disseminated through research meetings, peer-reviewed publications, the internet, and public media sources.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.