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

化学系的环境化学科学项目支持哥伦比亚大学的V.Faye McNeill教授和犹他州立大学的Yi Rao教授的这一项目。该项目解决了大气颗粒表面如何独特地影响那里发生的化学反应的问题。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化学。直到最近，由于缺乏能够探测表面特定粒子化学的分析技术，这种理解还受到限制。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。它们是表面特定和频率产生(SFG)和高灵敏超拉曼散射(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，以表征气溶胶表面独有的过程。除了对两所学院的研究生和本科生进行培训外，该小组还将开展外联活动，旨在接触到科学和工程领域中代表性较低的群体的学生和普通公众。表面特定粒子化学将在三个场景中进行研究：(1)乙醛在气相-气溶胶界面上的酸催化齐聚，(2)甲氧基酚在水相气溶胶中反应形成的光吸收产物，以及随后的液-液相分离，以及(3)小颗粒，预计其表面和本体之间具有尖锐的压力梯度，对水中反应速率(拉普拉斯压力)有影响。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为这种新的化学物质开发代表。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.