Surface Plasmon Modes of Sandwich-Like Metal–Dielectric Nanostructures

Abstract

We established that metal–dielectric nanostructures (consisting of three stacked monolayers of silver nanoparticles incorporated into polymer cross-linked film) can demonstrate three different surface plasmon collective modes. The modes were detected when the extinction spectra of the nanostructures were studied as a function of the incident angle and polarization of the incident light. Two previously known surface plasmon collective modes, namely T and P, associated with particle dipoles parallel and perpendicular to plane of the layer were identified for the polymer films containing one, two, and three monolayers of the particles. The extinction bands of T and P modes exhibited different intensity and frequency dependences on the angle of incidence. More pronounced angular dependences for P mode band indicated the stronger coupling of dipoles for P mode than for T one. A new N mode was observed for the structures consisting of three nanoparticle layers. This mode originated from surface plasmon coupling between adjacent layers. The additional mode significantly increases amount of information that can be obtained from optical response of the nanostructures.