Collaborative Research: Atmospheric Nanoparticle Growth from Nitrate (NO3) Radical Initiated Oxidation of Monoterpenes

该项目将实验室研究结果与数值模拟相结合，以研究大气中微小纳米颗粒的生长。了解这些微小颗粒的生长是很重要的，因为它们会影响云滴的形成和性质。这项研究将导致一个机制模式的发展，以更好地预测气溶胶对气候和空气质量的影响。将进行实验室实验，以确定和量化NO3自由基与三种常见单萜烯反应的气相和颗粒相产物：&amp；#945；蒎烯,,# 946;-蒎烯、3-蒈烯和一种额外的化合物&amp；#945；-thujene，结构类似于&amp；#945；-蒎烯，也应该形成气相产物，对纳米颗粒的生长贡献最小。这些实验将在一系列NO3浓度、湿度和温度下进行。计算化学研究将提供对NO3自由基氧化单萜烯可能的反应机制和纳米颗粒生长的深入了解。该项目的三个目标是：(1)实施计算化学方法来阐明反应途径和开发CIMS检测策略；(2)进行NO3自由基引发单萜烯氧化的对比实验室研究；(3)气相前驱体与纳米颗粒物理化学性质之间的化学闭合。通过该项目开发的纳米颗粒生长的过程级模型将使用实验测量的生长速率进行测试。纳米粒子的生长直接关系到这些粒子影响云凝结核数量和云滴形成和性质的能力。这个合作项目包括一个“近同行”项目，将加州大学欧文分校的研究生与里德学院的本科生配对，以促进科学互动，并为本科生的研究生学习做好准备。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。

This project combines the results of laboratory studies with numerical modeling to investigate the growth of tiny nanoparticles in the atmosphere. It is important to understand the growth of these tiny particles because they can influence the formation and properties of cloud droplets. This research will lead to the development of a mechanistic model to better predict the influence of aerosol on climate and air quality. Laboratory experiments will be conducted to identify and quantify the gas- and particle-phase products of the reactions of NO3 radicals with three common monoterpenes: α-pinene, β-pinene, 3-carene, and an additional compound, α-thujene, which is structurally similar to α-pinene and should likewise form gas phase products that contribute minimally to nanoparticle growth. These experiments will be conducted for a range of NO3 concentrations, humidities, and temperatures. Computational chemistry studies will provide insight into possible reaction mechanisms and nanoparticle growth due to monoterpene oxidation by NO3 radicals.The three objectives of the project are: (1) Implement computational chemistry methods for elucidating reaction pathways and developing CIMS detection strategies; (2) Perform comparative laboratory studies of NO3 radical initiated oxidation of monoterpenes; and (3) Obtain chemical closure between gas phase precursors and nanoparticle physicochemical properties. The process-level model for nanoparticle growth, developed through this project, will be tested using experimentally measured growth rates. Nanoparticle growth is directly tied to the ability of these particles to influence cloud condensation nuclei populations and affect the formation and properties of cloud droplets. This collaborative project includes a "near-peer" program that pairs University of California at Irvine graduate students with Reed College undergraduates in order to facilitate scientific interactions and to prepare the undergraduates for graduate study.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.