Dependent scattering and absorption of radiation by small particles

This study presents an analytical model to account for the effects of inter-particle interactions on the radiative characteristics of densely-packed homogeneous particulate systems. Departure from the assumption of independent scattering and absorption of radiation originates from two mechanisms: coherent addition (i.e., taking into account the phase differences) of the far-field scattered radiation and perturbation of the internal field of each particle by the presence of other particles. Dependent scattering has been previously studied by considering the first mechanism only. Dependent absorption, which is due to the latter, has not been considered in the literature even though absorption is more important than scattering in the extinction of radiation by small (Rayleigh) absorbing particles. This paper outlines a method to model the dependent absorption characteristics of dense particulate systems as well as a complete model for evaluating the dependent scattering. Statistical averages based on the random character of the particulate medium are introduced to obtain simple expressions for the above