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Measurement of the Optical Extinction Coefficients of Post-Flame Soot in the Infrared



J F. Widmann, Jiann C. Yang, Samuel L. Manzello, George W. Mulholland


The optical extinction coefficients of post-flame soot have been measured in the wavelength range 2.8 micrometers to 4.1 micrometers. A laminar diffusion burner was combined with an infrared spectrograph and gravimetric measurements to determine the mass specific extinction coefficient, sigma, and the dimensionless extinction coefficient, Ke. Using ethene gas as the fuel, the burner was operated at four global equivalence ratios (phi = 0.8, 1.0, 2.0, and 3.0) to examine the effect of the fuel-air ratio on the extinction coefficient. The extinction coefficient was found to decrease with increasing values of the global equivalence ratio for phi = 1.0, 2.0, and 3.0. The results for phi = 0.8 and phi = 1.0 were in agreement to within the uncertainty of the measurements. Measurements were obtained using propane gas as the fuel (phi = 1.0) and resulted in extinction coefficients equivalent to those of ethene.
Combustion and Flame
No. 1/2


fire suppression, fire detection, fire research, fire safety, fire protection, soot, infrared radiation, radiative heat transfer, smoke, radiative absorption


Widmann, J. , Yang, J. , Manzello, S. and Mulholland, G. (2003), Measurement of the Optical Extinction Coefficients of Post-Flame Soot in the Infrared, Combustion and Flame, [online], (Accessed July 25, 2024)


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Created July 1, 2003, Updated February 19, 2017