Tuning Optical Properties in Nanocomposites

Abstract

Metal nanostructures and noble metal-based nanostructures, in particular, exhibit plasmonic resonance in the visible region. The resonance absorption can be tuned by varying the size of nanoparticle and the external matrix in which the plasmonic materials are embedded. Mie’s theory has been used to demonstrate the shift in the plasmonic resonance in gold nanoparticles embedded in different dielectric media. Two model systems, viz. Au–ZnO and Au–Al2O3, prepared by sputtering on quartz substrates were used to study the optical absorption. The plasmonic peaks were observed to be red shifted in Au–Al2O3 and Au–ZnO, as is also supported by Mie formalism. The dielectric constant of the external matrix viz., Al2O3 and ZnO, estimated using the experimental and the Mie simulations are 3.05 and 1.83, respectively.