Atmospheric Chemistry of Low Volatility Organic Compounds

提出的研究目的是提高对大气有机气溶胶的化学和微物理性质的认识。这些气溶胶在大气中发挥着重要作用：它们的影响范围从城市和区域空气污染对人类健康的影响到气候变化对太阳辐射的散射。这里提出的工作旨在提供涉及原型低挥发性有机化合物的非均相化学过程的定量测量。所采用的技术利用具有可移动注射器的低压流管耦合到用于分析气态反应物和生成物的化学电离质谱仪；低挥发性有机反应物将以薄膜形式沉积在流管表面。薄膜的组成将由红外和/或拉曼光谱监测。具体项目包括研究低挥发性有机物质与OH、O2、NO和NO2的反应，依次和/或同时注入流管。要研究的有机物质有烷烃、多环芳烃和酸。研究了类异戊二烯与臭氧的反应。通过监测水蒸气的吸收，将研究暴露于各种气态反应物之前和之后有机薄膜的吸湿行为。此外，还将研究各种类型的有机化合物在几种不同基质上的吸附性能。

The objective of the proposed research is to improve the understanding of the chemical and microphysical properties of atmospheric organic aerosols. These aerosols play important roles in the atmosphere: their impacts range from human health effects in urban and regional air pollution to scattering of solar radiation in climate change.The work proposed here is designed to provide quantitative measurements on heterogeneous chemical processes involving prototype low volatility organic compounds. The technique to be employed utilizes a low pressure flow tube with a moveable injector coupled to a chemical ionization mass spectrometer for analysis of gaseous reactants and products; the low volatility organic reactants will be deposited as films on the flow tube surface. The composition of the films will be monitored by infrared and/or Raman spectroscopy.Specific projects to be carried out include investigations of the reactions of the low volatility organic species with OH, O2, NO and NO2, to be injected into the flow tube sequentially and/or simultaneously. The organic species to be studied are alkanes, polycyclic aromatic hydrocarbons (PAHs) and acids. The reaction of isoprenoids with ozone will also be studied. The hygroscopic behavior of the organic films will be investigated before and after exposure to the various gaseous reactants by monitoring the uptake of water vapor. Furthermore, the adsorption properties of the various types of organic compounds under study will be investigated on several different substrates.