0403829 Buckley The objective of this research is the development of a novel aerosol spectrometer that is able to quantitatively measure both size and composition of suspended aerosol particles. Size selection will be performed by a combination of fluidic separation and electronic mobility; particles will be charged and separated in a flowing stream using a variable electric field designed for point spectroscopy measurements. Composition determination will be accomplished with two-tone ultraviolet (UV) micro Laser-Induced Breakdown Spectroscopy (u-LIBS). The u-LIBS diagnostic head will selectively sample spatially size-segregated aerosol. Light will be dispersed into a new echelle spectrometer with a CCD camera, an optional relay lens intensifier and a high framing rate. Submicron particles are important in many areas of science, from the development of new materials with unusual properties, to pharmaceutical applications, to environmentally important suspended aerosol particles that are implicated in human morbidity and mortality. Real-time methods that can provide both size and composition information are urgently needed in all of these areas, and the availability of these methods would represent an enabling technology that could catalyze further advances in our understanding of nanoscale particle science. The particular example of atmospheric and combustion aerosol source-apportionment outlined in the technical proposal highlights one of the areas in which the proposed aerosol spectrometer could contribute to revolutionary fundamental advances. There are three specific areas of innovation that are expected provide improved performance for this new spectrometer design. They are: 1) The combination of fluidic and electrostatic size classification of particles coupled for point spectroscopic measurement, 2) The use of UV u-LIBS to provide highly spatially-resolved (and thus size-resolved) aerosol diagnostic with potentially improved detection limits over typical LIBS arrangements, and 3) The use of a sensitive, high frame-rate echelle spectrometer to provide elemental composition over a wide spectral range, allowing nearly total composition determination and identification of elemental associations in the aerosol population. As detailed in the proposal, both (2) and (3) and are particularly high-risk. UV u-LIBS has never been attempted on aerosol particles, and it is not known if the expected benefits will accrue. In addition, the high frame-rate echelle spectrometer is a new product and its applicability and sensitivity for this problem has yet to be determined. Previous approaches to point sizing and composition of submicron aerosol particles have met with limited success, particularly for sizes below 300 nm. The approaches outlined in the proposal have strong justification and promise, but this is clearly exploratory research. Lower risk options are in place to ensure meaningful results from the project should the higher-risk technologies fail to perform as expected. The proposed research would also have a substantial impact on the education and training of students in the interdisciplinary intersection of spectroscopy and nanoscale science. The resulting aerosol spectrometer would itself provide significant improvement in the instrumentation available for simultaneous particle composition and sizing analysis, which would open new avenues in both education and research. In particular, the proposed instrument could have an enormous impact on the identification and eventual mitigation of unhealthy atmospheric nanoparticles.
