Measurement of the Optical Extinction Coefficient of Combustion-Generated Aerosol
J F. Widmann, J X. Duchez, Joseph M. Conny, George W. Mulholland
This note describes mesurements of the optical extinction coefficient of carbonaceous aerosol produced during hydrocarbon combustion. Measurements of the mass specific extinction coefficient were obtained by laser extinction at 632 nm wavelength. The aerosol was generated using a laminar diffusion flame, and the extinction coefficient determined as a function of the global equivalence ratio. The black carbon content of the aerosol was also determined with respect to the equivalence ratio. A relationship was developed between the elemental carbon/total carbon (EC/TC) ratio and the optical extinction coefficient. The contribution to the extinction coefficient due to scattering was estimated to be approximately 15 %, thus the measurements provide a reasonable estimate of the absorption coefficient of combustion-generated aerosol. This note also present a simple method of producing laboratory aerosol with controlled EC/TC ratio.