Localized plasmon resonances in inhomogeneous metallic nanoclusters

A simple model of a disorder metallic nanocluster, using the previously developed discrete dipole approximation method, shows that very intense and relatively sharp plasmon resonances can be sustained inside these clusters at frequencies different from the intrinsic surface plasmon resonance ωp of the metal. These resonances come from random constructive interferences inside the clusters and can completely dominate their optical properties in both absorption and emission. Their relevance to the understanding of some of the many puzzling optical properties of metallic nanoclusters, and their role in single molecule detection by surface enhanced Raman scattering, is highlighted and discussed.