Plasmon Modes and Substrate-Induced Fano Dip in Gold Nano-Octahedra

Abstract

In this work, we have carried out a systematic study on the optical properties of gold nano-octahedra via numerical simulations. We obtained broadening scattering spectra dominated by a hybridized bonding mode originated from the interaction between intrinsic plasmon modes when increasing the size of gold nano-octahedra in vacuum. Once placing the nano-octahedra on a high refractive index dielectric substrate, a Fano dip can be induced in the scattering spectra due to the mutual interference between a dipolar mode and a quadrupolar mode. Moreover, we found that the interference become stronger by increasing the refractive index in substrate, and the broadening scattering spectra split into two hybridized modes in a single gold nano-octahedron: the anti-bonding mode and the bonding mode. Our results for the first time give a clear description of the complex plasmonic properties of a gold nano-octahedron and provide insights in designing appropriate nano-octahedral structures for applications.

Facet Tunability of Aluminum Nanocrystals

“…The multipole analysis indicates that the quadrupole mode is more strongly excited under P-polarization, likely due to the influence of the dielectric substrate. 56 The plasmon modes observed are consistent with those observed previously with octahedra 57 and truncated bitetrahedra 58,59 of other metals, with energies shifted due to the differing metal dielectric functions.…”

Periodic Arrays of Dewetted Silver Nanostructures on Sapphire and Quartz: Effect of Substrate Truncation on the Localized Surface Plasmon Resonance and Near-Field Enhancement

“…The weak central peak, which is indiscernible in experimental data, is likely attributable to a substrate-induced Fano resonance. 45,46 The t f = 1/5 spectra also show a prominent dipole and quadrupole peak but where the central peak is obscured by the dipole resonance. As is the case for colloidal structures, an increase in a nanostructure diameter leads to an increased absorbance and a red shift in the resonant frequency but where the shift is to a lesser degree for the quadrupole resonances.…”

Substrate-modulated directional far field scattering behavior of individual plasmonic nanorods

“…It is such gap localizing effect leads to the lower intensity of scattering spectra of the structure in figure 1(c). For g = 0 nm, n = 1.45, most of the electric field energy is symmetrically distributed on the side of the rod near the dielectric substrate, which is a large substrate damping effect derived quasi-dipole plasmon mode [24,29].…”

“…The far field scattering properties of plasmonic structures are highly sensitive to the metal micro-nanostructures dielectric constant, geometrical parameters, coupling parameter and the local dielectric environment [20]. Compared to the freestanding structures that embedded in homogeneous media, the introduction of dielectric substrates has a significant impact on the plasmonic properties of the supported micronanostructures due to the symmetry breaking of the environmental surrounding metal structures [21][22][23][24][25][26][27][28][29][30]. The far field behavior of substrate supported metal structures plays a very important role in plasmon applications such as directed scattering of electromagnetic energy and optical imaging [14,18].…”