Coupled plasmon in the rounded Ag hexagonal nanoplate dimer

Abstract

The subtle changes in the edges and corners of nanoparticles are the common occurrence during the manufacturing process of them which it affects on the nanoparticles sensing properties. In this work, we studied rounding effect on sensing properties of silver hexagonal nanoplate dimer by using the discrete dipole approximation (DDA). In these nanoplates three main plasmonic bands arise (dipole, octupole and anti-bonding modes). Both dipole and octupole modes are strongly affected by changes in the refractive index of medium and blue shift under the influence of the edges rounding. Our results show that hexagonal dimers with the least gap distance (g = 1 nm) have the largest extinction cross section and the maximum hybridization of plasmon peak.Furthermore, our results show that octupole mode has the highest FOM in both types of perfect and rounded hexagonal nanoplate's dimer, and the FOM of rounded hexagonal dimer is less than the perfect hexagonal nanoplate dimers. This study may be used to build more advanced sensing devices based on metallic nanoparticles.