American Association for Aerosol Research - Abstract Submission

AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA

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Identification of Airborne Particles by Forward Light Scattering

PAUL LANE, Matthew Hart, Brian Saar, Jay Eversole, Naval Research Laboratory

     Abstract Number: 530
     Working Group: Aerosol Physics

Abstract
Environmental, health and security concerns are driving our interest in techniques to characterize airborne particles in real time. The primary cause of attenuation of incident radiation in aerosols is scattering, which is a function of the complex refractive index and the size and shape of particles. Light scattering varies significantly over wavelengths near an absorption maxima, because the complex refractive index is changing rapidly over this interval. This feature can be exploited to determine the absorption peak(s) of a particle, and hence, indicate its composition. Using silica particles as a test case, we show that we can differentiate bare particles from those thinly coated by an organic dye with an absorption maxima using three incident lasers selected with wavelengths slightly above and below this peak. Experimental results on spherical and nonspherical particles will be presented and compared to scattering theory.