Absorption and scattering of light from ensembles of randomly oriented aggregates.

This paper presents one approach to the absorption and scattering of light from aggregates of primary particles. The primary particles are sphere-like and small compared to the wavelength, whereas the aggregate can be large compared to the wavelength. This situation applies to when soot particles formed in flames are measured using methods based on laser light. The method presented in this work, called generalized Rayleigh-Debye-Gans, leads to closed-form expressions for the scattered intensity and the absorbed power of an ensemble of aggregates with random positions and orientations. The expressions ensure a fast and accurate numerical evaluation of the scattering and absorption from ensembles of aggregates. The numerical results are compared with the ones obtained from the T-matrix method and the discrete dipole approximation method.