Journal Article

FZJ-2015-06788

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Assessing Optical Properties and Refractive Index of Combustion Aerosol Particles Through Combined Experimental and Modeling Studies

Kim, J. ; Bauer, H. ; Dobovičnik, T. ; Hitzenberger, R. ; Lottin, D. ; Ferry, D. ; Petzold, A. (Corresponding author)FZJ*

2015
Taylor & Francis Philadelphia, Pa

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Please use a persistent id in citations: doi:10.1080/02786826.2015.1020996

Abstract: The variability of optical properties of combustion particles generated from a propane diffusion flame under varying fuel-to-air (C/O) ratios was studied with a three-wavelength nephelometer, a particle soot absorption photometer, and an integrating sphere photometer. Information on particle size distribution, morphology, and elemental carbon to total carbon (EC/TC) ratios were obtained from scanning mobility particle sizer measurements, transmission electron microscopy analyses, and thermal-optical analyses. Particles generated under a low C/O ratio (0.22) showed high elemental carbon fraction (EC/TC = 0.77) and low brown carbon to equivalent black carbon (BrC/EBC) ratio (0.01), and were aggregates composed of small primary particles. Rayleigh–Debye–Gans theory reproduced experimental single-scattering albedo, ω, absorption, and scattering Ångström exponents within 56, 3, and 18%, respectively. In contrast, particles produced under a high C/O ratio (0.60) showed low elemental carbon fraction (EC/TC = 0.09) and high BrC/EBC ratio >100, and were smaller and spherical in shape. Their optical properties were better modeled with Mie theory. By minimizing the difference between calculated and measured ω and Ångström exponents, refractive indices of OC at three visible wavelengths were deduced. Contrary to the widely accepted assumption that refractive index of BC is wavelength independent, BC-rich particles exhibited absorption Ångström exponent >1.0 which implies some degree of wavelength dependence.

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. 243 - Tropospheric trace substances and their transformation processes (POF3-243) (POF3-243)

Appears in the scientific report 2015

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Database coverage:
; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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