Collaborative Research: Laboratory Investigations of Particle-Organic Vapor Interactions: Effects on Particle Formation, Growth, and Properties

该项目是四个机构之间的合作努力，以增进对大气气溶胶基本生命周期的了解。这项工作的重点是在一系列条件下在大气中形成非常小的颗粒的过程。拟议研究的目标是通过进行实验室测量来减少与模拟这些颗粒物的形成、生长和对大气的重要性质相关的不确定性，从而促进对这些颗粒物对气候的影响的更准确的预测。项目团队拥有广泛的能力，包括产生诸如烟尘和二次有机气溶胶(SOA)的初级气溶胶颗粒、测量和控制颗粒的大小和质量分布、通过羟基自由基和臭氧反应控制这些颗粒在相当的大气寿命内的氧化老化，从几小时到几天不等，控制无机和有机颗粒涂层的生产，测量气体和凝聚相有机化合物的化学成分，测量生成粒子的云凝聚核(CCN)活性，并测量粒子的光学性质。拟议的三年实验室研究计划将提供有关SOA作为氧化处理功能的相关物理化学性质的详细信息，包括气相前体与凝聚的SOA的相互作用。SOA颗粒将在传统的环境箱中产生，以及在最近开发的流动反应器中产生，该反应器可以在广泛的模拟大气条件下高通量地产生SOA。流动反应器能够控制与大气相关的气相和凝聚相有机化合物的羟基自由基(OH)氧化。在反应器中的停留时间比在环境箱中可获得的停留时间短约两个数量级(几分钟而不是几天)，而OH浓度高出两到三个数量级。该项目将为模拟和预测气溶胶在气候变化中的作用提供一个更可靠的数据库，并有助于详细了解碳质气溶胶的化学、物理和光学性质是如何相互联系的，以及它们如何随着氧化老化而发生变化。

This project is a collaborative effort among four institutions to improve understanding of the fundamental life cycle of atmospheric aerosol. The effort focuses on processes for the formation of very small particles in the atmosphere over a range of conditions. The goal of the proposed studies is to facilitate more accurate predictions of the influence of these particles on climate by conducting laboratory measurements that reduce uncertainties related to modeling their formation, growth and atmospherically important properties.Together the project team has extensive capabilities that include the ability to produce primary aerosol particles such as soot and secondary organic aerosol (SOA), measure and control the particle size and mass distributions, control oxidative aging of such particles via hydroxyl radical and ozone reactions over equivalent atmospheric lifetimes ranging from hours to multiple days, control production of both inorganic and organic particle coatings, measure the chemical composition of gas- and condensed-phase organic compounds, measure the cloud condensation nuclei (CCN) activity of generated particles, and measure particle optical properties.The proposed three-year laboratory research program will provide detailed information on relevant physiochemical properties of SOA as a function of oxidative processing, including interactions of gas-phase precursors with the condensed SOA. The SOA particles will be generated in conventional environmental chambers as well as in a more recently developed flow reactor that can produce SOA with high throughput over a wide range of simulated atmospheric conditions. The flow reactor enables controlled hydroxyl radical (OH) oxidation of atmospherically relevant gas phase and condensed-phase organic compounds. The residence time in the reactor is about two orders of magnitude shorter (minutes rather than days) and the OH concentration is two to three orders of magnitude higher than is attainable in environmental chambers. This project will provide a more reliable database for modeling and predicting the role of aerosols in climate change and lead to a detailed understanding of how the chemical, physical and optical properties of carbonaceous aerosols are interconnected and how they change as a function of oxidative aging.