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

该项目由一系列研究组成，旨在测量由各种气相前体氧化形成的二次有机气溶胶（SOA）对半挥发性有机化合物（SVOC）的吸收系数。这些研究的基本原理是，SOA增长可以通过动态限制机制来更好地描述，而不是基于平衡阶段划分的机制，并且为了更准确地建模SOA增长，需要在典型的大气SOA中使用各种SVOC的吸收系数。然而，SOA的吸收系数数据是有限的。因此，这些活动包括研究SOA的生成和组成，这是由硝酸盐自由基或/和臭氧在大容量、慢流的气溶胶流管内氧化SOA前体形成的；研究有机硝酸盐和SVOC在SOA上的吸收，以及使用衰减全反射傅立叶变换红外光谱法（ATR-FTIR）研究SOA组件可能蒸发的情况；使用Knudson电池和涂覆壁快流反应器测量SOA对有机硝酸盐和SVOC的绝对吸收系数；有机硝酸盐和SVOC在自组装单层膜上的吸附特性以及利用纳米二次离子质谱法（nano-SIMS）分析SOA。这项研究将产生重要的信息，以评估SOA增长中动态限制机制与均衡划分的相对重要性。更广泛的影响包括提供半挥发性有机化合物进入二次有机气溶胶的动力学数据和分子见解，通过出版物广泛传播结果，夏季教师研讨会，为学生和公众举办实验室参观，研究人员访问当地学校，培训本科生和研究生和博士后，继续参与首席研究员的研究活动中代表性不足的群体。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.