PLASMONIC NANOPARTICLES AS VERSATILE NANORULERS FOR SENSING APPLICATIONS: DEVELOPING THE NANOPARTICLE-ON-MIRROR ARCHITECTURE

Abstract

The basis of plasmonic sensors is the resonant coupling between the oscillations of free electrons, called plasmons, and incident visible light waves. By confining these oscillations within a nanostructure, the coupling efficiency is enhanced by the creation of localized surface plasmon resonant (LSPR) states. The frequency at which these oscillations occur is dependent upon a number of factors, one of which is the proximity of another plasmonic nanoparticle. The relationship between the frequency of the LSPR oscillations and the distance separating the nanoparticles is called the plasmon nanoruler (PNR). This phenomenon is highly distance dependent - a measurement of the LSPR for a plasmonic nanoparticle allows a researcher to calculate the interparticle separation for length scales well beneath the diffraction limit for visible light. However, even with the enhanced coupling between the nanoparticle and incident light, the signal from a single nanoruler is very dim, and adequate control over many nanorulers is difficult to achieve.