Mesostructured metallic substrates composed of square pyramidal pits are shown to confine localized plasmons. Plasmon frequency tuning is demonstrated using white light reflection spectroscopy with a wide range of structure dimensions from $400\text{to}3000\mathrm{nm}$. Using a simple plasmon cavity model, we demonstrate how the individual pit morphology and not their periodicity controls the resonance frequencies. By measuring the surface-enhanced Raman scattering (SERS) signals from monolayers of benzenethiol on the same range of mesostructures, we extract a quantitative connection between absorption, field enhancement, and SERS signals. The match between theory and experiment enables effective design of plasmon devices tailored for particular applications, such as optimizing SERS substrates.

• Received 13 October 2006

DOI:https://doi.org/10.1103/PhysRevB.76.035426