Dual wavelength sensing based on interacting gold nanodisk trimers

Abstract

Fabrication and surface plasmon properties of gold nanostructures consisting of periodicarrays of disk trimers are reported. Using electron beam lithography, disk diameters assmall as 96 nm and gaps between disks as narrow as 10 nm have been achieved with anunprecedented degree of control and reproducibility. The disk trimers exhibit intense visibleand infrared surface plasmon resonances which are studied as a function of the diskdiameter and of the pitch between trimers. Based on simulations of the optical extinctionspectra and of the electric near-field intensity maps, the resonances are assigned to asingle trimer response and to collective surface plasmon excitations involvingelectromagnetic interaction between the trimers. The sensing properties of thedisk trimers are investigated using various coating media. The reported resultsdemonstrate the possible use of gold disk trimers for dual wavelength chemical sensing.