Characterization of Carbonaceous Particles: Aerosol Mass Spectrometry and Light Scattering

Aerosol particles have important effects on visibility, acid deposition, climate, and human health. A large fraction of the anthropogenic aerosol is generated from energy-related activities, and organic compounds are known to constitute a significant fraction of ambient aerosol mass in many locations. Yet, large uncertainties remain in quantifying the chemical composition and atmospheric transformations of these aerosols, especially with respect to organic particulate matter. Particularly lacking are real-time, size-resolved, quantitative instruments for the identification, speciation, and source apportionment of carbonaceous aerosols. An innovative thermal desorption, time-of-flight aerosol mass spectrometer recently has been developed with capabilities that can fill a critical need for size-resolved, quantitative chemical composition data on aerosol particles. This project will develop and demonstrate a light scattering module for this instrument, which will enable full characterization of carbonaceous components, including their state of mixing (and atmospheric aging), along with other chemical components such inorganics and dust. In Phase I, the light scattering system was optimized and installed in a quadruople aerosol mass spectrometer, ray tracing calculations were performed to optimize optical detection, software for analyzing data on individual particles in real-time was developed, and the system capabilities were quantified. Phase II will continue the development of the light scattering module and its incorporation into the new time-of-flight aerosol mass spectrometer. The combined instrument will be tested on multiple aerosol systems in the laboratory and during a future field study. Commercial Applications and other Benefits as described by the awardee: Beyond the application for atmospheric research, the combined aerosol mass spectrometer and light scattering module could provide aerosol measurement capabilities for a variety of monitoring applications. A portable instrument could be employed in industrial process monitoring and chemical and biological warfare agent identification. In addition, the instrument is ideally suited for the characterization and control of aerosol emissions from production processes that produce aerosol laden exhaust, including semiconductor manufacturing, gas turbines, fluidized bed combustors, diesel combustors, and conventional furnaces