9703615 Wexler This project supports the construction of a field-deployable Rapid Single-Particle Mass Spectrometer (RSMS). This instrument will be capable of providing chemical as well as size information on individual particles in the size range of 40 to 200 nm. This will be achieved by size selecting particles with a specially designed nozzle inlet, evaporating the particles using excimer laser radiation and analyzing the fragments using mass spectrometry. Chemical constituents such as organic carbon, elemental carbon, sulfates, methane sulfonates, and sodium chloride will be distinguishable. The information will be semi-quantitative due to shot-to-shot variations in signal intensity obtained with particles of identical composition, and due to a bias of the technique to surface species. However, chemometric data analysis techniques are capable of classifying the obtained spectra and extracting information on the aerosol composition and mixing state (external vs. internal). Once the assembly of the field-deployable instrument is completed, it will be tested at a local site to demonstrate the technique at ambient air conditions. The sizing technique will be calibrated and validated.
