Plasmonic gold-copper alloy dimer as ‘nanorulers’

Boundary element method (BEM) simulation has been utilized for performing electrodynamic simulation studies of metal nanostructures, to study the factors affecting the plasmons, design protocols to improve the plasmonic features and to develop newer areas of applications. Optical coupling studies of metal nanoparticles is considered as a major development in recent times, for efficiently enhancing and focusing the incident electromagnetic fields at the nanogap junctions between two metal nanoparticles, thus employing them as perfect plasmonic nanorulers. Herein, we have simulated the scattering cross section and near-field enhancement for nanodimers of monometallic gold, copper and bimetallic AuCu alloy nanoparticles, emphasizing the fact that apart from morphology, the plasmonic signatures are highly dependent on the dielectric constant of the constituent metal/surrounding medium. Our simulation data confirm the decrease in coupling effects when the interparticle distance is increased above 2 nm.