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Spectral dependence of visible light absorption by carbonaceous particles emitted from coal combustion
Author(s) -
Bond Tami C.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013652
Subject(s) - absorption (acoustics) , wavelength , materials science , visible spectrum , ultraviolet , combustion , optics , refractive index , carbon fibers , radiation , amorphous carbon , optoelectronics , physics , chemistry , raman spectroscopy , organic chemistry , composite number , composite material
Optical characteristics of particles that absorb visible light are needed to model their effects on atmospheric radiation. Light absorption by particles emitted from low‐technology coal combustion has exhibited a strong spectral dependence. I investigate various explanations for this phenomenon and conclude that a spectrally dependent imaginary refractive index is the most plausible. Following previous work on the structure of amorphous carbon, I propose that both the magnitude and spectral dependence of light absorption are controlled by the size of graphitic clusters within the material, and can be described using the optical band‐gap theory. This hypothesis is an alternative to the current measurement divisions of light‐absorbing “black carbon” and non‐absorbing “organic carbon,” and offers an explanation for preferential absorption at blue wavelengths that may extend to ultraviolet wavelengths.