Nanorice: a hybrid plasmonic nanostructure.

We have designed and fabricated a new hybrid nanoparticle that combines the intense local fields of nanorods with the highly tunable plasmon resonances of nanoshells. This dielectric core-metallic shell prolate spheroid nanoparticle bears a remarkable resemblance to a grain of rice, inspiring the name "nanorice". This geometry possesses far greater structural tunability than either a nanorod or a nanoshell, along with much larger local field intensity enhancements and far greater sensitivity as a surface plasmon resonance (SPR) nanosensor than any dielectric-metal nanostructures reported previously. Invoking the plasmon hybridization picture allows us to understand the plasmon resonances of this geometry, as arising from a hybridization of the primitive plasmons of a solid spheroid and an ellipsoidal cavity inside a continuous metal.