Detection of Bioaerosols using Single Particle Thermal Emission Spectroscopy (First-year Report)

Report No. ARL-TR-5934
Authors: Dr. Kristan P. Gurton, Melvin Felton, and Dr. Yongle Pan
Date/Pages: February 2012; 20 pages
Abstract: We are investigating a new type of single aerosol particle spectroscopy that is designed to identify unique and identifiable characteristic features in measured molecular emission/absorption spectra in the thermal infrared (IR) region from 3 to 12 μm. Our objective is to improve the ability to identify and distinguish mundane bioaerosols from more toxic varieties and/or species. During year 1 of a two-year study, we developed and investigated various techniques required for single bioparticle generation, transfer, and manipulation. During the second year, our goal will be to directly measure in situ the gray-body spectral emission from a 1–20 micron size bioparticle that is optically heated to temperatures of approximately 100–300 °C above ambient temperatures. The resultant thermal emission is dispersively resolved using 190-mm Horiba spectrometer that houses a time-gated 32-element mercury cadmium telluride (MCT) linear array. In this report, we outline the fundamental theory for our approach, discuss in detail the various single particle transport and trapping methods required to conduct single particle thermal emission spectroscopy (SPTES) in situ, and present the result that we photophoretically trapped weak absorbing bioaerosol particles by laser bottle beam via optical aberration.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2012