Light-induced coherent interactions between silver nanoparticles in two-dimensional arrays.

Silver nanoparticles arranged in two-dimensional arrays experience quadrupolar coupling of plasmon resonances when irradiated with visible light. This coupling leads to the formation of the coherent plasmon mode characterized by an intense narrow resonance in the blue spectral range in the extinction spectrum. The coupling and the intensity of this mode can be effectively controlled by varying the distance between particles. The interparticle distance was varied by biaxial stretching of the arrays prepared in transparent elastomeric film of poly(dimethylsiloxane). The observed phenomenon exemplifies a generic approach in which new optical properties of materials can be engineered by organizing metal nanoparticles in various one-, two-, and three-dimensional structures. Further development of this approach will result in the discovery of novel principles of both fundamental and practical importance.