BEATING BIOAEROSOLS


THIS PROJECT ADDRESSES A DOD NEED TO BETTER UNDERSTAND ESPECIALLY


THE PROPERTIES AEROSOLIZED SUCH


TO DETECT AGENTS


OF BIOWARFARE


ORDER TO IMPROVE THE USE OF INSTRUMENTS DESIGNED OF


CONCENTRATIONS AMID


MOSTLY INNOCUOUS BACKGROUND PARTICLES.


crucial adjustments: sealing them from ambient air exposure, and rotating the chamber to keep the particles inside sus- pended longer for scientists to study.


SAMPLING SINGLE PARTICLES ARL researchers, led by Dr. Yongle Pan, measured the fluorescence spectra of individual particles sampled from the


drum using the Single-Particle Fluores- cence Spectrometer (SPFS) developed in cooperation with Yale University. Te SPFS makes real-time measurements of single-particle ultraviolet (UV)-laser- induced fluorescence spectra excited by two pulsed lasers. Te fluorescence spec- tra and amplitudes measured, and the effects of sunlight, ozone, other oxidants, terpenes, etc., on this fluorescence are central to several bioagent detectors that have been deployed by DOD and the U.S. Department of Homeland Security.


TEST CHAMBERS


In their field experiments at ARL Headquarters in Adelphi, MD, the research team used two drums containing Aerosol Chambers for Evolution Studies. One was filled with natural polluted air from the outside environment, and the other with highly purified air, allowing the team to measure how bioaerosols are affected by the environment. (Photo by Doug LaFon, ARL)


“Te particles are drawn into the cell by a partial vacuum. When a particle scatters light from both of the focused different-wavelength diodes, so that the light detected by each of the two photo- multiplier tubes exceeds a threshold, then the UV laser fires, and the intensified charge-coupled device detector is gated on so it can record the particle’s laser- induced fluorescence spectrum,” said Pan, of ARL’s Atmospheric Sensing Branch, who developed the device with Dr. Ron- ald Pinnick and Dr. Steven Hill at ARL and Dr. Richard Chang, Henry Ford II Professor of Applied Physics at Yale.


ARL sampled atmospheric particles every hour during the field testing


104


BIOAEROSOLS, AGENTS,


IN


Army AL&T Magazine


January–March 2013


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