Passive and Active Standoff Infrared Detection of Bio-Aerosols
PHYSICAL SCIENCES INC ANDOVER MA
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Biological compounds are known to have infrared spectra indicative of specific functional groups. There is a strong interest in the use of passive means to detect airborne biological particles, such as spores and cells, which may act as biological weapons. At the sizes of interest, the infrared spectra of bacterial particles results from a combination of geometric pi dsub particle lambda and Mie pi dsub particle approx. lambda scattering processes while the infrared spectrum of atmospheric particles falls into the Rayleigh limit pi dsub particle lambda. In this paper we report on laboratory measurements of the infrared spectra of aerosolized Bacillus subtilis BG spores in air under controlled measurement conditions. Transmission measurements show an IR spectrum of the spores with features comparable to the condensed phase spectrum superimposed on a background of Mie scattering. Preliminary measurements indicate a peak extinction coefficient of approximately 1.6 x 10exp -8sq cm per spore at 9.65 micrometers. These results are discussed in terms of their implication for passive and active infrared detection and identification of bio-aerosols.
- Chemical, Biological and Radiological Warfare