HR: 0800h
AN: A31C-0065    [Abstracts]
TI: Effect of Coatings on Laser Induced Incandescence (LII) of Soot
AU: * Gershenzon, M
EM: mygersh@sandia.gov
AU: Witze, P O
EM: witze@sandia.gov
AU: Michelsen, H A
EM: hamiche@sandia.gov
AB: Combustion-generated soot is the most significant contributor to positive radiative forcing by atmospheric aerosols. The exact magnitude of this forcing is, however, highly uncertain due to (1) the lack of an accurate global inventory of atmospheric black carbon aerosol distributions and (2) an inadequate understanding of the optical properties of such particles, associated with their complex morphology and composition. Therefore, both development of new techniques for characterizing realistic soot particles and detailed investigations of their optical properties are needed for a reliable assessment of the direct forcing by anthropogenic black carbon. We present laboratory studies exploring applicability of the laser induced incandescence technique to quantitative detection of black carbon aerosols in the atmosphere. In these experiments, sulfuric-acid-coated soot particles were sampled with a scanning mobility particle sizer (SMPS) and detected with LII to yield the following information: (1) the sensitivity of LII to black carbon as a function of SMPS-derived coating thickness and (2) the degree of coating desorption and soot fragmentation as a function of laser fluence. The energy balance equation was solved to model the particle-laser interactions, accounting forparticle heating by light absorption and cooling by radiative emmission, conduction, sublimation, and coating evaporation, and the results were compared with experimental data.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting