AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Real Time Absorption Spectra of Smoke from Smoldering Combustion
Rian You, James Radney, Michael Zachariah, CHRISTOPHER ZANGMEISTER, National Institute of Standards and Technology
Abstract Number: 452 Working Group: Aerosols, Clouds, and Climate
Abstract Biomass burning (BB) is a large contributor to carbonaceous aerosols in the terrestrial atmosphere. High in mass concentration, but weakly absorbing across the visible portion of the spectrum, much of the BB is formed from smoldering smokes. In this study absorption spectra of laboratory produced smoldering smokes from six types of wood were investigated. Absorption data were measured in situ between 500 nm and 840 nm using a photoacoustic spectrometer and a step-scanning a supercontinuum laser source coupled to a tunable wavelength and bandwidth filter. Smoldering smoke particles were mobility and mass-selected prior to optical characterization allowing data to be reported as mass-specific absorption cross sections (MAC). The measured MAC at 500 nm was time dependent, ranging from 0.25 m2g-1 and gradually dropped to 0.03 m2 g-1 within 12 min of smoldering initiation. All six materials studied had a median MAC ranging between 0.026 m2 g-1 to 0.133 m2 g-1 at a wavelength of 500 nm and absorption Ångström exponents (AAE) ranged between 3.7 to 5.6. It was shown both experimentally and computationally that weakly absorbing smoldering smoke particles behave as volume absorbers for particles in excess of 750 nm.