Laboratory Studies of Heterogeneous Chemistry in the Upper Troposphere/Lower Stratosphere

小行星9711969 在这一项目中，将对对流层上部/平流层下部相关条件下的粒子形成和多相化学反应进行实验室研究。极地平流层云（PSC）的组成、形成机制和丰度仍不确定，对流层上部非均相化学的作用尚未确定。 为了探测粒子的形成，将进行几种类型的实验。首先，FTIR反射吸收光谱（RAS）将用于对大气物质的均匀和非均匀成核参数进行基本测量。扩散激活能和接触参数将被确定为成核理论提供必要的输入。其他实验室实验将探索PSC的形成机制，特别是Ia型PSC，其确切组成仍然未知。 此外，还将对对流层上部具有潜在重要性的多相化学反应进行实验室研究。最丰富的粒子类型被认为是卷云，亚可见卷云和硫酸盐气溶胶。将使用Knudsen池流动反应器与FTIR RAS耦合以探测凝聚相。将研究含氧有机物和凝结在卷云颗粒上的硝酸之间可能发生的氧化/还原反应，并将进行潮解和结晶硫酸盐反应性的实验。

9711969 Tolbert In this project, laboratory studies of particle formation and heterogeneous chemical reactions under conditions relevant for the upper troposphere/lower stratosphere will be performed. The composition, formation mechanism and abundance of polar stratospheric clouds (PSCs) remain uncertain, and the role of heterogeneous chemistry in the upper troposphere has not been established. To probe particle formation, several types of experiments will be performed. First FTIR reflection absorption spectroscopy (RAS) will be used to make fundamental measurements of homogeneous and heterogeneous nucleation parameters for atmospheric materials. Diffusion activation energies and contact parameters will be determined to provide the necessary input for nucleation theory. Other laboratory experiments will probe the formation mechanisms of PSCs, in particular, type Ia PSCs, whose exact composition is still unknown. In addition, laboratory studies of heterogeneous chemical reactions of potential importance in the upper troposphere will be performed. The most abundant types of particles there are thought to be cirrus, subvisible cirrus, and sulfate aerosols. A Knudsen cell flow reactor coupled with FTIR RAS to probe the condensed phase will be used. Oxidation/reduction reactions that may occur between oxygenated organics and nitric acid condensed on cirrus particles will be studied, and experiments on the reactivity of deliquesced and crystalline sulfate salts will be performed.