Coarse Mode Aerosol Analyzer

Coarse mode aerosols have recently been attracting significant attention because of their role in Earth’s radiative budget, impact on the carbon cycle, biogeochemistry, and adverse effects on human health. The lack of research on coarse mode aerosols is partially caused by difficulties in handling and measuring them. Measurements of coarse mode aerosols are extremely important, which includes the sources, physical characteristics, chemical composition, and size distributions, to develop predictive understanding of their properties and their contribution to a variety of atmospheric processes, biogeochemical cycles, and the global radiative budget. This SBIR project will develop an instrument to characterize chemical composition and particle size distribution of coarse mode aerosols by implementing single-particle laser induced breakdown spectroscopy (SP-LIBS). LIBS provides information on elemental composition by detecting and analyzing atomic spectra resulting from breakdown of aerosol particles in hot plasma formed by a focused high-energy laser pulse. The goal is to develop a technology to classify the LIBS spectra of natural coarse-mode aerosol particles in order to identify biological aerosols of different origin (pollen, bacteria, spores, etc.) and various types of mineral dust, with an added capability of sizing the aerosol particles. The Phase I project will demonstrate the feasibility of the proposed approach, which includes: (1) designing and building a laboratory prototype of the SP-LIBS analyzer with added capability of particle sizing; (2) characterizing the analyzer using monodisperse and polydisperse coarse mode aerosols of known compositions; (3) using biological and mineral dust standards to generate a preliminary library of reference SP-LIBS spectra, and demonstrating classification of the aerosol standards and natural aerosols using data reduction approaches; (4) determining specifications for the main components of the coarse mode aerosol analyzer and identifying the engineering challenges of transitioning the technology to a field-deployable prototype in Phase II. Successful completion of this Phase I/II program will lead to development of a commercial coarse mode aerosol analyzer compatible with ground-based, marine, and aerial platforms. Ground-based deployment may include combining multiple instruments into a decentralized wireless mesh network capable of providing temporally- and spatially-resolved information on coarse mode aerosols. When carried over into Phase III and beyond, this project will be of great benefit to the public and Federal Government. Availability of accurate and extensive data on the chemical composition and size distributions of coarse mode biological and mineral aerosols will lead to better understanding of their sources, physical characteristics, and contribution to biogeochemical cycles and the global radiative budget. Other potential applications include detection of biological warfare agents, and characterization of volcanic ash plumes and industrial aerosols.