RESONANT LIGHT-SCATTERING BY FRACTAL CLUSTERS

A scale-invariant theory of resonant Rayleigh scattering by fractal clusters is developed. Our main result is that the scattering cross section is greatly enhanced, because of the presence of very high local fields, which are correlated and strongly fluctuating. Simulations dealing with two examples of fractal structures, namely, random walk and cluster-cluster aggregates, are presented. The numerical results confirm the theoretical predictions of the scaling behavior for both absorption and scattering, and allow us to obtain the corresponding exponents. In addition to the results for scattering, the large scale of the simulations of the present work provides a comprehensive confirmation and a substantial extension of a recent study by Markel, Muratov, Stockman, and George [Phys. Rev. B 43, 8183 (1991)].