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Title: Effects of aggregate morphology and size on laser-induced incandescence and scattering from black carbon (mature soot)

We have used a Single-Particle Soot Photometer (SP2) to measure time-resolved laser-induced incandescence (LII) and laser scatter from combustion-generated mature soot with a fractal dimension of 1.88 extracted from a burner. We have also made measurements on restructured mature-soot particles with a fractal dimension of 2.3–2.4. We reproduced the LII and laser-scatter temporal profiles with an energy- and mass-balance model, which accounted for heating of particles passed through a CW-laser beam over laser–particle interaction times of ~10 μs. Furthermore, the results demonstrate a strong influence of aggregate size and morphology on LII and scattering signals. Conductive cooling competes with absorptive heating on these time scales; the effects are reduced with increasing aggregate size and fractal dimension. These effects can lead to a significant delay in the onset of the LII signal and may explain an apparent low bias in the SP2 measurements for small particle sizes, particularly for fresh, mature soot. The results also reveal significant perturbations to the measured scattering signal from LII interference and suggest rapid expansion of the aggregates during sublimation.
Authors:
 [1] ;  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
1244114
Report Number(s):
SAND-2015-0193J; SAND-2015-6102J
Journal ID: ISSN 0021-8502
Grant/Contract Number:
AC04-94AL85000
Type:
Published Article
Journal Name:
Journal of Aerosol Science
Additional Journal Information:
Journal Volume: 88; Journal ID: ISSN 0021-8502
Publisher:
Elsevier
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 54 ENVIRONMENTAL SCIENCES; Soot; Black carbon; LII; Scattering; SP2; Morphology; 36 MATERIALS SCIENCE; soot; black carbon; scattering; morphology