Collaborative Research: Surface-specific Aerosol Chemistry: Direct Observations, Kinetics, and Environmental Impact

化学系的环境化学科学计划支持哥伦比亚大学的V. Faye麦克尼尔教授和州立大学犹他州的Yi Rao教授的这个项目。该项目研究了大气颗粒物表面如何独特地影响那里发生的化学反应。为了量化人类活动对空气质量和气候的影响，需要更好地了解大气颗粒物化学。直到最近，这种理解受到缺乏能够探测表面特定颗粒化学的分析技术的限制。该团队开发了独特的实验室方法，用于在实验室环境中研究悬浮在气体中的颗粒的化学性质。它们是表面特异性和频产生（SFG）和高灵敏度超拉曼散射（HRS）。这些技术将与互补的气体-颗粒化学动力学研究一起应用，以表征气溶胶表面特有的过程。除了在这两个机构培训研究生和本科生外，该团队还将参与旨在接触科学和工程领域代表性不足的学生以及普通公众的外联活动。表面特定粒子化学将在三种情况下进行研究：（1）乙醛在气体-气溶胶界面上的酸催化低聚，（2）甲氧基酚在含水气溶胶中反应形成吸光产物，以及它们随后的液-液相分离，和（3）预期在表面和本体之间具有急剧压力梯度的小颗粒，其暗示了水反应速率（拉普拉斯压力）。该团队还将进行数值模拟，以评估这些过程的潜在环境影响，并在大规模大气模型中开发这种新化学的代表性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

The Environmental Chemical Sciences Program of the Division of Chemistry supports this project by Professors V. Faye McNeill at Columbia University and Yi Rao at Utah State University. The project addresses how surfaces of atmospheric particles uniquely affect the chemical reactions taking place there. A better understanding of atmospheric particle chemistry is needed for quantifying the impacts of human activities on air quality and climate. Until recently, this understanding was limited by a lack of analytical techniques capable of probing surface-specific particle chemistry. The team has developed unique laboratory methods for studying the chemistry of particles suspended in gas in a laboratory setting. These are surface-specific sum frequency generation (SFG) and highly-sensitive HyperRaman Scattering (HRS). These techniques will be applied together with complementary gas-particle chemical kinetics studies to characterize processes that are unique to aerosol surfaces. In addition to the training of graduate and undergraduate students at both institutions, the team will also engage in outreach activities designed to reach students from underrepresented groups in science and engineering, and the general public.Surface-specific particle chemistry will be investigated in three scenarios: (1) the acid-catalyzed oligomerization of acetaldehyde at the gas-aerosol interface, (2) the formation of light-absorbing products from the reactions of methoxyphenols in aqueous aerosols, and their subsequent liquid-liquid phase separation, and (3) small particles which are expected to have a sharp pressure gradient between the surface and bulk, with implications for aqueous reaction rates (Laplace pressure). The team will also conduct numerical simulations in order to evaluate the potential environmental impact of these processes and develop representations for this new chemistry in large-scale atmospheric models.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.