Optical scattering by metallic and carbon aerosols of high aspect ratio

The iterative extended boundary condition method (IEBCM) is utilized to calculate scattering and absorption by metallic colloids and carbon aerosols in the 0.4-μm < λ < 10-μm optical wavelength range. The colloids and aerosols were modeled by dielectric spheroids of high aspect ratio. The new IEBCM method is found to be suitable for making calculations for particles with aspect ratios as high as 12. Results are presented for silver and aluminum metallic aerosols as well as for atmospheric aerosols such as soot and iron oxides (magnetite). The various parameters used to examine the convergence of the IEBCM solution, such as the number of subdomain expansions and the size of the incremental change in intermediate object sizes used in the iterative process, are discussed. Using the internal field distribution to test the convergence of the results is also found to be more accurate than the traditional procedure which utilizes extinction and scattering cross-section data.