Self-assembly of metallic nanoparticles into plasmonic rings

Metallic nanoparticles are self-assembled into plasmonic nanorings. The self-assembly is evaporation-induced and is driven using a template of dielectric microspheres. We obtain well-ordered arrays of metallic nanorings over large areas. The inner and outer diameters of the rings, as well as the pitch of the array, are fully controllable. The optical resonances supported by the plasmonic rings are then characterized using extinction spectroscopy. Our approach opens a simple and inexpensive road to create plasmonic structures that can find applications as metamaterials or substrates for enhanced spectroscopies.