Surface Plasmon Excitation in a Spherical Nanocavity: The Hydrodynamical Drude Model

We theoretically study nonlocal effects in surface plasmon excitations in a spherical dielectric nanocavity embedded in a metallic host within the framework of the hydrodynamic Drude model. An analytical expression for the surface plasmon resonance frequencies is derived, enabling a transparent interpretation of size-dependent and material-dependent plasmonic behavior beyond the local approximation. Nonlocality is shown to modify the plasmonic response, leading to a blueshift of the resonance frequencies as the nanocavity radius decreases. We further demonstrate that the background dielectric constant associated with the metal ion core plays an essential role in the excitation process. For nanocavities with dielectric constants smaller than that of the metallic background, the surface plasmon resonances shift to higher frequencies, while a redshift occurs when the cavity dielectric constant exceeds the background value. In addition, increasing the nanocavity dielectric constant enhances the influence of nonlocal effects on surface plasmon excitations. These parameters offer valuable guidance for the design of subwavelength plasmonic structures.

کلیدواژه ها:

Localized surface plasmons ، Spatial nonlocality effects ، Spherical nanocavity ، Surface Plasmon