The effects of the local dielectric environment on the surface-plasmon resonances of annealed metal-island films are studied experimentally and modeled theoretically. Silver-island films were annealed to produce spheroidal shaped particles which exhibit well-resolved resonances in polarized, angle-resolved, absorption spectra. These resonances are shifted in different amounts by the depolarizing interaction with the underlying substrate. They are also affected by additional dielectric coverages or separation of the particle film from the substrate. Cross-section calculations based upon a nonretarded, single-particle, dielectric interaction for these various configurations are presented and found to be in agreement with experimental observations.

• Received 23 September 1986

DOI:https://doi.org/10.1103/PhysRevB.35.3753