AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Infrared Elastic Scattering Spectroscopy of Individual Aerosol Particles
WILLIAM HERZOG, Jonathan Richardson, Brian Saar, David Wolinski, Jason Jong, Jay D. Eversole, Lincoln Laboratory, Massachusetts Institute of Technology
Abstract Number: 289 Working Group: Instrumentation and Methods
Abstract We have performed chemical composition classification of individual micron-sized aerosol particles using infrared elastic scattering spectroscopy. We describe electromagnetic scattering calculations and experiments that demonstrate that the absorption features of single aerosol particles may be inferred from the particle’s spectrum of elastically scattered infrared light.
An experimental setup was constructed to collect infrared elastic scattering spectra from individual aerosol particles. A Wavelength Beam Combined-Quantum Cascade Laser (WBC-QCL) array was used as the multi-wavelength, long-wave infrared (LWIR) source to illuminate individual aerosol particles entrained in an airflow. Elastically scattered light from each individual aerosol particle was collected onto a single-element HgCdTe detector. A variety of materials, including laboratory particle standards such as polystyrene latex spheres and poly-methyl methacrylate spheres were measured. For a few of the materials, the complex index of refraction versus wavelength was available for use in computational scattering modeling. Mie scattering calculations were performed that show good agreement with experimental results. This work demonstrates that single-aerosol particle infrared elastic scattering spectroscopy can be used as a fingerprint of the vibrational modes of aerosol materials to allow differentiation of aerosol species based upon their chemical structure in real time on a particle-by-particle basis.