Angular Scattered Light Intensity of Dipole–Multipole Plasmonic Hybridization
Min Xi, Shenyi Ding, Nian Li, Zhenyang Wang
Abstract
The coupled plasmonic modes of noble metal nanoparticles are of interest in fields spanning chemistry, physics, materials science, and biology. We systematically investigated the near- and far-field optical response of a dipole–multipole (D–M) coupled gold nanorod (Au NR) dimer structure. We show that the coupling behavior of D–M resonances leads to redshifted bonding and blueshifted antibonding modes that are analogous to the dipole–dipole coupling observed in the plasmon hybridization framework of Nordlander et al. In particular, the antibonding modes of Au NR dimers are very similar to multipolar resonances of the Au NR monomer of equivalent overall length. These antibonding modes show almost identical far-field plasmon resonance peaks and near-field distribution and also have similar far-field angular radiation profiles with even stronger intensities. We also evaluated Au NR dimer structures of different gap distances in terms of near-field intensities, phase changes, and angular scattering patterns, which exhibit coupling behavior ranging from strongly interacting D–M systems to uncoupled individual elements over a variety of gap distances. Our studies may advance the fundamental understanding of D–M coupled plasmonic systems and pave the path to new opportunities for nanoplasmonic applications, such as fluorescence imaging, energy storage, biosensors, metamaterials, etc.