Development of an Integrated System for Analyses of Aerosol Composition and Chemistry

这项主要研究仪器(MRI)的建议是开发一个综合的实验室系统来表征气溶胶的组成和化学。三个分析子系统将被组装并整合成一个独特而强大的系统，用于研究被认为在地球大气中重要的气溶胶颗粒的组成、尺寸分布和反应性。通过雾化器和流态化喷雾器等常用技术，将产生大小和化学成分可控的颗粒。气溶胶将由差示迁移率分析仪和空气动力学粒度仪进行表征，然后注入压力和温度控制流动系统，类似于用于研究高活性自由基和弱结合物种的系统。在这个反应室中，颗粒将暴露在不同浓度的气体中，如硝酸、水蒸气、无机酸和有机化合物。稳定物种(包括反应物和产物)的气相组成将通过可调谐二极管激光光谱(TDLS)、化学电离质谱仪(CIMS)和傅里叶变换红外光谱(FTIR)进行监测。利用光学散射技术对颗粒的数量和尺寸分布进行现场监测。最后，粒子将通过空气动力学入口聚焦到真空室，在那里它们将通过气溶胶飞行时间确定大小，并通过质谱仪确定其组成。该项目的长期目标是建立一个多学科的气溶胶科学中心，促进大学、国家实验室和工业界研究人员之间的密切合作。

This Major Research Instrumentation (MRI) proposal is to develop a comprehensive laboratory system to characterize the composition and chemistry of aerosols. Three analytical subsystems will be assembled and integrated into a unique and powerful system for studying the composition, size distribution, and reactivity of aerosol particles believed to be important in the earth's atmosphere. Particles of controlled size and chemical composition will be generated with commonly used techniques such an atomizer and a fluidized bed nebulizer. The aerosols will be characterized by differential mobility analyzers and aerodynamic particle sizers and subsequently injected into a pressure- and temperature-controlled flow system similar to those employed for studies of highly reactive radicals and weakly bound species. In this reaction chamber the particles will be exposed to variable concentrations of gases like nitric acid, water vapor, inorganic acids, and organic compounds. The gas-phase composition of stable species (both reactants and products) will be monitored by tunable diode laser spectroscopy (TDLS), chemical ionization mass spectrometry (CIMS), and Fourier transform infrared spectroscopy (FTIR). The particle number and size distributions will be monitored in situ by optical scattering techniques. Finally, the particles will be focused through an aerodynamic inlet into a vacuum chamber where they will be sized by aerosol time-of-flight and their composition determined by mass spectrometry. The long-term goal of this project is to establish a multidisciplinary center for aerosol science which will foster close collaborations between investigators in universities, national laboratories, and industry.