AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Detection and Characterization of Chemical Aerosol Using Laser Trapping Single-Particle Raman Spectroscopy
AIMABLE KALUME, Joshua Santarpia, Yong-Le Pan, U.S. Army Research Laboratory, Adelphi, MD
Abstract Number: 31 Working Group: Instrumentation and Methods
Abstract Studying physical and chemical properties of aerosol particles in the ambient medium presents a unique tool in order to understand their dynamics, evolution and effects on our environment. In this perspective, a rapid detection and characterization of the presence of chemical agent aerosols in various complex atmospheric environments is an essential defense mission. Despite considerable efforts vowed to prevent the development, production, stockpiling and the use of chemical weapons, the World faces a constant sense of threat and fear, resulting from the increasing criminal and terrorist activities. Our research focuses on characterizing chemical agents and simulants as airborne aerosol particles. Recently, we developed a laser-trapping single-particle Raman spectrometer system, we trapped and characterized microdroplets of the VX nerve agent chemical simulant, diethyl phthalate. In additional to the good agreement with previous works and theoretical prediction, the uniqueness of the chemical fingerprint is enhanced by appearance of additional spectral features, related to the spherical nature of the microdroplets, namely stimulated Raman scattering and morphology-dependent whispering gallery modes. The resonance spectrum, resulting from the variations in the elastic scattered light as function of time, was compared to the simulation, based on Lorenz-Mie theory, to determine the microdroplet size at any given time. Due to its high efficiency in trapping and its precision in spectroscopic characterization, this method could be particularly suitable for detecting and characterizing hazardous substances such as chemical agents in complex atmospheric environments.