An ansatz for the distribution of depolarization factors, based on a theory of the optical response of nearly touching spheres, is used to calculate the optical absorption of a medium containing isolated clusters of small metallic spheres. The calculated absorption agrees qualitatively with experiments over the entire frequency range. In the far-infrared region we find enhanced absorption and predict a small deviation from an ${\omega }^2$ frequency dependence.

• Received 24 February 1986

DOI:https://doi.org/10.1103/PhysRevB.33.7956