Open AccessFractal morphology of black carbon aerosol enhances absorption in the thermal infrared wavelengths
Author(s) -
William R. Heinson,
Rajan K. Chakrabarty
Publication year - 2016
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.41.000808
Subject(s) - optics , absorption (acoustics) , rayleigh scattering , wavelength , carbon black , infrared , materials science , thermal , mie scattering , refractive index , fractal , aerosol , phase (matter) , carbon fibers , molecular physics , physics , scattering , light scattering , thermodynamics , meteorology , mathematical analysis , natural rubber , mathematics , quantum mechanics , composite material , composite number
In this Letter, we numerically calculate the mass absorption cross sections (MACs) of black carbon fractal aggregates in the thermal infrared solar spectrum. Compared to equivalent-size spheres, the MAC values of aggregates show a percent enhancement of ≈150 and 400 at small and large length scales, respectively. The absorption properties of aggregates with size parameters >1 surprisingly continued to remain in the Rayleigh optics regime. We explain this phenomenon using the Maxwell-Garnett effective medium theory and the concept of phase shift parameter.