Development of Critical Data for Predicting Growth of Secondary Organic Aerosols in Air

该项目包括一系列研究，以测量半挥发性有机化合物(SVOC)在由各种气相前体氧化形成的二次有机气溶胶(SOA)上的吸收系数。这些研究的基本原理是，与基于平衡相分配的机制相比，动力学受限的机制可以更好地描述SOA增长，并且需要各种SVOC在典型大气SOA上的吸收系数才能更准确地模拟SOA增长。然而，关于SOA的吸收系数数据是有限的。因此，这些活动包括研究SOA前体被硝酸根或/和臭氧在大容量慢流气溶胶流动管中氧化形成的SOA的生成和组成；研究有机硝酸盐和SVOC在SOA上的吸收以及利用衰减全反射傅立叶变换红外光谱(ATR-FTIR)研究SOA组分的可能蒸发；使用克努森池和涂层壁式快速流动反应器测量有机硝酸盐和SVOC对SOA的绝对吸收系数；表征有机硝酸盐和SVOC在自组装单层上的吸收；以及使用纳米二次离子质谱仪(Nano-SIMS)分析SOA。这项研究将产生重要的信息，用于评估动力受限机制与平衡分配在SOA增长中的相对重要性。广泛的影响包括提供关于二次有机气溶胶吸收半挥发性有机化合物的动力学数据和分子见解，通过出版物、暑期教师研讨会、为学生和公众主办的实验室之旅广泛传播结果、研究人员访问当地学校、培训本科生和研究生以及博士后研究员、未被充分代表的群体继续参与首席研究员的研究活动，以及为加州大学欧文分校的本科课程开发新的实验。

This project is comprised of a series of studies to measure the uptake coefficients for semi-volatile organic compounds (SVOC) on secondary organic aerosols (SOA) formed from the oxidation of a variety of gas phase precursors. The rationale for these investigations is that SOA growth is better described by a kinetically limited mechanism than one based on equilibrium phase partitioning, and that uptake coefficients for various SVOC on typical atmospheric SOA are needed in order to model SOA growth more accurately. However, uptake coefficients data on SOA are limited. The activities therefore include studies of the generation and composition of SOA formed from oxidation of SOA precursors by nitrate radical or/and ozone inside a large-volume, slow-flow aerosol flow tube; studies of the uptake of organic nitrates and SVOC on SOA as well as studies of possible evaporation of SOA components using attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR); measurements of absolute uptake coefficients of organic nitrates and SVOC on SOA using a Knudson cell and a coated wall fast flow reactor; characterization of the uptake of organic nitrates and SVOC on self-assembled monolayers; and analysis of SOA using nano-secondary ion mass spectrometry (nano-SIMS). The research will yield information important in assessing the relative importance of kinetically limited mechanisms versus equilibrium partitioning in SOA growth.Broader impacts include providing kinetic data and molecular insights on the uptake of semi-volatile organic compounds onto secondary organic aerosol, disseminating results broadly through publications, summer teacher workshops, hosted lab tours for students and the general public, visits of researchers to local schools, training of undergraduate and graduate students and postdoctoral fellows, continued involvement of underrepresented groups in the principal investigator's research activities, and development of new experiments for the undergraduate curriculum at UC-Irvine.