ABSORPTION AND ELASTIC-SCATTERING OF LIGHT BY PARTICLE AGGREGATES

Light scattering and absorption by spherical particles is extended to aggregates of spheres with arbitrary shape and size. We applied the th eory of Gerardy and Ausloos [Phys. Rev. B 25, 4204-4229 (1982)] to com pute the total extinction loss spectra of several aggregates of nanome ter-sized silver spheres from the near IR to the near UV. Silver was b est suited to provide quantitative comparison with experiments concern ing the scattering and absorption in the visible spectral region. Addi tional resonant extinction was obtained besides the resonant extinctio n of the single silver sphere. The spectra were discussed in detail to give general results that are independent of the particle material.