Composite Nanostructures for Enhanced Plasmonics

Abstract

Enhancement in plasmonic response of metal nanoparticles in the form of metal/metal oxide nanocomposites is very interesting from both the theoretical understanding and application. Metal based oxide/Ag nanocomposites were synthesized by polyol process. Metal oxide nanoparticles present in nanocomposites as core and noble metal as a shell are of interest in investigation of plasmonic behavior of noble metals and sensing application. Cobalt ferrite (CoFe2O4) and ZnO were used as oxide core in the form of spherical and rod nanostructures respectively. Presence of Ag was confirmed by XRD and SEM analysis. In this paper we summarize the synthesis and characterization of plasmonic properties of composite nanostructures. Optical absorption studies performed on CoFe2O4@Ag and ZnO@Ag exhibit sharp plasmonic resonance but shifted towards lower wavelength (blue shift). An attempt has been made to explain this shift using the Mie scattering calculations based on size variation and change in the dielectric of the surrounding medium.