Plasmon Coupling in Self-Assembled Gold Nanoparticle-Based Honeycomb Islands

Abstract

Metallic nanostructures that sustain plasmonic resonances are indispensable ingredients for many functional devices. Whereas structures fabricated with top-down methods entail the advantage of a nearly unlimited control over all plasmonic properties, they are in most cases unsuitable for a low cost fabrication on large surfaces; and eventually a truly nanometric size domain is difficult to reach due to limitations in the fabrication resolution. Although ordinary bottom-up techniques based on colloidal nanolithography promise to lift these limitations, they often suffer from their incapability to self-assemble nanoparticles at large surfaces and at a density necessary to observe effects that strongly deviate from those of isolated nanoparticles. Here, we rely on the application of sequential bottom-up fabrication steps to realize honeycomb structures from gold nanoparticles that show strong extinction bands in the near-infrared. The extraordinary properties are only facilitated by densely packing the nanoparticles into clusters with a finite size; causing the clusters to act as plasmonic macromolecules. These strongly interacting bottom-up materials with a deterministic geometry but fabricated by self-assembly might be of use in future sensing applications and in material platforms to mediate strong light−matter-interactions.

Single step synthesis and organization of gold colloids assisted by copolymer templates

“…The presence of a peak at larger wavelength can be explained by longitudinal modes due to very close interacting plasmonic nanoparticles as already observed in [15]. Indeed, when nanoparticles are densely packed (dimer approximation), strong plasmon coupling can occur and gives rise to extinction peaks at larger wavelength [38]. As expected, this coupling mode is blue-shifted with increasing the concentration from 4% to 6% due to the decrease of the NP size.…”

Ag@Au core–shell nanoparticles synthesized by pulsed laser ablation in water: Effect of plasmon coupling and their SERS performance

“…2-4, reveals that for core- shell nanostructures with relatively thick Au deposition, the plasmon band look-like a monotonic curve, and shift its position when the volume of suspension was reduced (Table 1). This transformation of the two distinct plasmon bands to a monotonic one and the shift in wavelengths can be attributed to the plasmon-plasmon coupling taking place in the Ag@Au core-shell nanostructures when the interparticle distance (d) is reduced [13][14][15][16][17][18][19][20]. This near field interaction between nanoparticles depends on the distance of separation between the particles [14], and can be described using the plasmon hybridization model referred as the electromagnetic analogue of molecular orbital theory [16].…”

“…This transformation of the two distinct plasmon bands to a monotonic one and the shift in wavelengths can be attributed to the plasmon-plasmon coupling taking place in the Ag@Au core-shell nanostructures when the interparticle distance (d) is reduced [13][14][15][16][17][18][19][20]. This near field interaction between nanoparticles depends on the distance of separation between the particles [14], and can be described using the plasmon hybridization model referred as the electromagnetic analogue of molecular orbital theory [16]. It has already been reported that when nanoparticles come closer, within 2.5 times of the particle diameter, causes interaction of their localized surface plasmon resonances in the vicinity of two nearer particles and give rise to polarization dependent plasmon-plasmon coupling effect [15,18].…”

“…The localized surface plasmons of neighbouring nanostructures can interfere each other, when they are too close, and result in the formation of new plasmon band [13][14][15]. This plasmon-plasmon coupling offers another mechanism for the manipulation of light at the nanoscale.…”

Facile Preparation of Ultrasmall Void Metallic Nanogap from Self‐Assembled Gold–Silica Core–Shell Nanoparticles Monolayer via Kinetic Control

“…The two SPR bands in the visible and near-IR range can be attributed to the strong near-fi eld coupling between the nanoparticles due to the decrease in interparticle distance upon the removal of the SiO 2 shell. [ 35 ] To further elaborate on the SiO 2 shell-etching rate, we performed EFTEM measurement to visualize the change in the SiO 2 shell of individual Au@SiO 2 nanoparticles after various etching time ( Figure S6, Supporting Information). EFTEM results show that the silica thickness of individual Au@SiO 2 nanoparticles on TEM grid is decreased and the silica layer is completely removed after about 150 min.…”