RUI: Secondary Organic Aerosol and Brown Carbon Formation from Aldehydes, Ammonium Salts, and Amines

这个项目将表征大气水相化学和棕色碳的形成，目标是两种化合物：乙醇醛和羟丙酮。其他常见的大气醛，如乙醛和甲醛，虽然预计不会形成棕色碳，但仍可能通过与铵盐和胺的反应形成大量二次有机气溶胶(SOA)材料。在存在α-二羰基的情况下，这些化合物可以并入咪唑产品中，因此将在存在和不存在α-二羰基的情况下检查它们形成SOA的潜力。将使用一套方法。首先，我们将用腔衰减相移和紫外-可见(UV-Vis)光谱研究棕色碳的形成。产品结构将通过质子核磁共振波谱和电喷雾电离质谱仪进行表征。吸湿性、串联差示迁移率分析和拉曼显微镜将被用来测量反应产物的吸水率和表面活性。反应速率将通过核磁共振和紫外可见光谱进行测量。根据具体实验的需要，气溶胶将由三种不同的方法产生。这些研究的目的将是识别和表征反应产物，测量反应速率和气体/颗粒分配，并确定这些SOA和棕色碳形成途径的大气意义。作为该项目的一部分，至少20名不同的本科生将接受第一次研究经验的指导，通过提供更多的学生研究机会，增强的研究基础设施，以及增加与本科生合著者的论文发表率，拓宽学生选择科学职业的渠道。增加一名博士后教师/研究员将使更多的学生得到指导，同时为职业生涯早期的科学家提供出色的培训。该领域将受益于对潜在的重要SOA和褐碳来源的描述，以及对一批不同的年轻科学家的培训。最后，棕色碳的形成与氨/胺排放之间的联系可能会为减少气溶胶形成提供新的途径，以改善空气质量和应对全球变暖。

This project will characterize atmospheric aqueous-phase chemistry and formation of brown carbon, targeting two compounds: glycolaldehyde and hydroxyacetone. Other common atmospheric aldehydes such as acetaldehyde and formaldehyde, while not expected to form brown carbon, may still form large amounts of secondary organic aerosol (SOA) material via reactions with ammonium salts and amines. In the presence of alpha-dicarbonyls, these compounds can be incorporated into imidazole products, so their SOA-forming potential will be examined with and without alpha-dicarbonyls present. A suite of methods will be used. First, brown carbon formation will be studied by cavity attenuated phase-shift and ultraviolet-visible (UV-Vis) spectroscopy. Product structure will be characterized by proton nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry. Hygroscopicity tandem differential mobility analysis and Raman microscopy will be used to measure water uptake and surface activity of reaction products. Reaction rates will be measured by NMR and UV-Vis spectroscopies. Aerosol will be generated by three different methods, as required for specific experiments. The aim of these studies will be to identify and characterize reaction products, measure reaction rates and gas/particle partitioning, and determine the atmospheric significance of these SOA and brown carbon formation pathways.At least twenty diverse undergraduate students will be mentored in first research experiences as part of this project, widening the pipeline of students choosing careers in science by offering more student research opportunities, an enhanced research infrastructure, and an increased publication rate of articles with undergraduate co-authors. The addition of a postdoctoral teacher / researcher will allow more students to be mentored while providing excellent training for an early-career scientist. The field will benefit from the characterization of potentially significant sources of SOA and brown carbon, and from the training of a diverse group of young scientists. Finally, a connection between brown carbon formation and ammonia / amine emissions may suggest new avenues for mitigating aerosol formation to improve air quality and address global warming.