Plasmonic Properties of Close-Packed Metallic Nanoparticle Mono- and Bilayers

Vieira, Bruno G. M.; Mueller, Niclas S.; Barros, Eduardo B.; Reich, Stéphanie

doi:10.1021/acs.jpcc.9b03859

Cited by 18 publications

(12 citation statements)

References 66 publications

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“…However, we have shown recently that an increased influence of field retardation in combination with the large refractive index of AuNP layers allows exciting dark plasmons in bilayers of hexagonally close-packed AuNP with visible light at normal incidence -given a sufficient particle size of more than approximately 30 nm. 10,14 As presented in Fig. 1b, for such a AuNP bilayer the excitation of a dark plasmon mode leads to an additional absorbance peak at the edge between the visible and near infrared spectrum.…”

Section: Theorymentioning

confidence: 93%

Dark plasmon modes for efficient hot electron generation in multilayers of gold nanoparticles

Hoeing

Schulz

Mueller

et al. 2020

The Journal of Chemical Physics

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The excitation of dark plasmons, i.e. coupled plasmon modes with a vanishing net dipole, is expected to favor Landau damping over radiative damping. The dark plasmon excitation might therefore lead to an increased absorption of energy within gold nanoparticles, resulting in a strong generation of hot electrons compared to the generation via bright plasmons. We performed transient-absorption spectroscopy on gold nanoparticle films to assess the initial electronic temperature before thermalization. We observe a significant increase in the electron-phonon coupling time if dark plasmon modes are excited in these films. The results indicate an efficient energy absorption within the nanoparticles due to the suppressed radiative decay of dark plasmon modes.

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Section: Theorymentioning

confidence: 93%

Dark plasmon modes for efficient hot electron generation in multilayers of gold nanoparticles

Hoeing

Schulz

Mueller

et al. 2020

The Journal of Chemical Physics

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“…To fit plasmon eigenenergies in the absorption spectra we subtracted a background due to the interband transitions of gold. We obtained the background functional form by calculating a slab of gold using identical parameters as for the oligomer simulation . The absorption spectra were fit by one (azimuthal, radial polarization) and three (linear) Lorentzian peaks.…”

Section: Methodsmentioning

confidence: 99%

“…Instead of the E 1 u mode, the E 1 g eigenstate is allowed for the retarded field and linearly polarized light. This mode has the two dipoles pointing in the opposite direction. , In a real experiment, the wavelength will neither be infinite nor match the dimer size, and both modes will contribute to the optical spectra. Indeed, optical experiments on hexagonal layers of nanoparticles observed absorption by a plasmon mode in the bilayer that was absent from the spectrum of a monolayer. , The mode had parallel dipoles within a layer, but antiparallel dipoles from one layer to the next, which corresponds to the E 1 g mode of the nanosphere dimer .…”

Section: Retardation Of the Incoming Lightmentioning

confidence: 99%

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

2020

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Structured light are custom light fields where the phase, polarization, and intensity vary with position. It has been used for nanotweezers, nanoscale imaging, and quantum information technology, but its role in exciting optical transitions in materials has been little examined so far. Here we use group theory to derive the optical selection rules for nanosystems that get excited by structured light. If the size of the nanostructure is comparable to the light wavelength, it will sample the full beam profile during excitation with profound consequences on optical excitations. Using nanooligomers as model nanosystems, we show that structured light excites optical transitions that are forbidden for linearly polarized or unpolarized light. Such dipole forbidden modes have longer lifetimes and narrower resonances than dipole allowed transitions. We derive symmetry-adapted eigenmodes for nanooligomers containing up to six monomers. Our study includes tables with selection rules for cylindrical vector beams, for beams with orbital angular momentum, and for field retardation along the propagation direction. We discuss multi-photon processes of nonlinear optics in addition to one-photon absorption. Structured light will unlock a broad range of excitations in nanooligomers and other nanostructures that are currently inaccessible to optical studies.

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“…Light is strongly confined inside a plasmonic supercrystal. 4 , 6 , 24 , 29 The electric field is situated outside the plasmonic nanoparticles because of the large dielectric contrast of metals and dielectrics in the near-infrared ( Figure 2 a). The near-field interaction between neighboring nanoparticles leads to a further confinement into hot spots at the interparticle gaps.…”

Section: Results and Discussionmentioning

confidence: 99%

“…FDTD simulations were conducted with the commercial software package Lumerical FDTD Solutions. The simulation layout was similar to our previous works. , Briefly, the unit cell of a hexagonally packed monolayer of gold nanospheres was constructed with periodic boundary conditions along x and y . The nanoparticle layers were then stacked along the z direction with the abc stacking sequence of an fcc crystal along [111].…”

Section: Methodsmentioning

confidence: 99%

Surface-Enhanced Raman Scattering and Surface-Enhanced Infrared Absorption by Plasmon Polaritons in Three-Dimensional Nanoparticle Supercrystals

et al. 2021

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Surface-enhanced vibrational spectroscopy strongly increases the cross section of Raman scattering and infrared absorption, overcoming the limited sensitivity and resolution of these two powerful analytic tools. While surface-enhanced setups with maximum enhancement have been studied widely in recent years, substrates with reproducible, uniform enhancement have received less attention although they are required in many applications. Here, we show that plasmonic supercrystals are an excellent platform for enhanced spectroscopy because they possess a high density of hotspots in the electric field. We describe the near field inside the supercrystal within the framework of plasmon polaritons that form due to strong light-matter interaction. From the polariton resonances we predict resonances in the far-field enhancement for Raman scattering and infrared absorption. We verify our predictions by measuring the vibrations of polystyrene molecules embedded in supercrystals of gold nanoparticles. The intensity of surface-enhanced Raman scattering is uniform within 10% across the crystal with a peak integrated enhancement of up to 300 and a peak hotspot enhancement of 10 5 . The supercrystal polaritons induce pairs of incoming and outgoing resonances in the enhanced cross section as we demonstrate experimentally by measuring surface-enhanced Raman scattering with multiple laser wavelengths across the polariton resonance. The infrared absorption of polystyrene is likewise enhanced inside the supercrystals with a maximum enhancement of 400%. We show with a coupled oscillator model that the increase originates from the combined effects of hotspot formation and the excitation of standing polariton waves. Our work clearly relates the structural and optical properties of plasmonic supercrystals and shows that such crystals are excellent hosts and substrates for the uniform and predictable enhancement of vibrational spectra.

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Plasmonic Properties of Close-Packed Metallic Nanoparticle Mono- and Bilayers

Cited by 18 publications

References 66 publications

Dark plasmon modes for efficient hot electron generation in multilayers of gold nanoparticles

Dark plasmon modes for efficient hot electron generation in multilayers of gold nanoparticles

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

Surface-Enhanced Raman Scattering and Surface-Enhanced Infrared Absorption by Plasmon Polaritons in Three-Dimensional Nanoparticle Supercrystals

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