The optical constants of carbonaceous materials derived from different types of fuel were determined by a polarized ratio reflectance technique over a spectral range of 0.5–0.75 µm and variable incident angles to compare the relative influence of composition independent of particle size and size distribution. Optical properties of soots from acetylene, propane, and kerosene fuels and from a carbon black were measured in the 0.5–0.75-µm spectral range and the spectral optical constants calculated. Differences in optical constants were observed for soots derived from different types of fuel and for soots derived from the same type fuel when volatile adsorbed species were removed by exposure to vacuum.
Carmen E. Batten, "Spectral optical constants of soots from polarized angular reflectance measurements," Appl. Opt. 24, 1193-1199 (1985)