Plasmonic Coupling Properties in Conductively Touched Metallic Ellipsoidal Dimer and Trimer

Abstract

The optical properties and plasmonic coupling of conductively touched homo-dimer and -trimer ellipsoidal nanoparticles composed of silver and gold structures were illustrated theoretically by using the discreet dipole approximation. I demonstrated for the first time the effect of the physical contact on the optical properties of coupled dimer and trimer at two extremes of the polarization angles. The results of the simulations show strong plasmonic couplings between the interacting induced dipole moments in both Ag and Au dimer and trimer when they are illuminated by longitudinal polarized light. The optical responses exhibit the excitation of several bright in-phase longitudinal plasmonic modes of different origin (dipole-dipole and quadrupole-quadrupole modes) with significant change in the resonance wavelength when the number of the coupled particles is increased. For the other orthogonal polarization state, the in-phase π*-antibonding coupled mode is observed in the absorption spectra with a weak plasmonic coupling detected from the unchanged band position of the excited peak. These observations are in good agreement with plasmon hybridization model.

Computational Study of the Effect of the Size-Dependent Dielectric Functions of Gold Nanomaterials on Optical Properties

“…Gold nanoparticle dielectric function modifies the resonance condition, damping factor, and radiative decay of surface plasmons, which in turn affects the optical density and extinction cross-sectional characteristics [89]. The ratio of the nanoparticles' dielectric function to that of the surrounding medium establishes the resonance condition, which in turn establishes the peak position.…”