Characterization of Nonradiative Bloch Modes in a Plasmonic Triangular Lattice by Electron Energy-Loss Spectroscopy

Yoshimoto, Daichi; Saito, Hikaru; Hata, Satoshi; Fujiyoshi, Yoshifumi; Kurata, Hiroki

doi:10.1021/acsphotonics.8b00936

Cited by 4 publications

(4 citation statements)

References 42 publications

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“…Previous observations of local dark modes by EELS, among other techniques, have been reported. 36,45,62 Nevertheless, the finding of extended (antiferroelectric) dark modes is also reported in this work.…”

Section: Resultssupporting

confidence: 78%

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Imaging of Antiferroelectric Dark Modes in an Inverted Plasmonic Lattice

et al. 2023

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Plasmonic lattice nanostructures are of technological interest because of their capacity to manipulate light below the diffraction limit. Here, we present a detailed study of dark and bright modes in the visible and near-infrared energy regime of an inverted plasmonic honeycomb lattice by a combination of Au + focused ion beam lithography with nanometric resolution, optical and electron spectroscopy, and finite-difference time-domain simulations. The lattice consists of slits carved in a gold thin film, exhibiting hotspots and a set of bright and dark modes. We proposed that some of the dark modes detected by electron energy-loss spectroscopy are caused by antiferroelectric arrangements of the slit polarizations with two times the size of the hexagonal unit cell. The plasmonic resonances take place within the 0.5−2 eV energy range, indicating that they could be suitable for a synergistic coupling with excitons in two-dimensional transition metal dichalcogenides materials or for designing nanoscale sensing platforms based on near-field enhancement over a metallic surface.

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Section: Resultssupporting

confidence: 78%

“…This kind of extended dark mode can be excited by EELS in the experimental sample as discussed below. Previous observations of local dark modes by EELS, among other techniques, have been reported. ,, Nevertheless, the finding of extended (antiferroelectric) dark modes is also reported in this work.…”

Section: Resultssupporting

confidence: 61%

Imaging of Antiferroelectric Dark Modes in an Inverted Plasmonic Lattice

et al. 2023

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“…As shown in the energy-filtered images (Fig. 1b and c), the excitation probabilities of the lower band edge modes are distributed to the entire top surface of the disks while those of the upper band edge modes are localized to the edges of the disks, indicating the same results as the previous study, that is, the lattice point modes are located at the lower band edges while the inter-lattice modes are located at the upper band edges [26]. Figs.…”

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confidence: 82%

Emergence of point defect states in a plasmonic crystal

et al. 2019

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Plasmonic crystals are well known to have band structure including a bandgap, enabling the control of surface plasmon propagation and confinement. The band dispersion relation of bulk crystals has been generally measured by momentum-resolved spectroscopy using far field optical techniques while the defects introduced in the crystals have separately been investigated by near field imaging techniques so far. Particularly, defect related energy levels introduced in the plasmonic band gap have not been observed experimentally. In order to investigate such a localized mode, we performed electron energy-loss spectroscopy (EELS), on a point defect introduced in a plasmonic crystal made up of flat cylinders protruding out of a metal film and arranged on a triangular lattice.The energy level of the defect mode was observed to lie within the full band-gap energy range.This was confirmed by a momentum-resolved EELS measurement of the band gap performed on the same plasmonic crystal. Furthermore, we experimentally and theoretically investigated the emergence of the defect states by starting with a corral of flat cylinders protrusions and adding sequentially additional shells of those in order to eventually forming a plasmonic band-gap crystal encompassing a single point defect. It is demonstrated that a defect-like state already forms with a crystal made up of only two shells.

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“…To characterize the plasmonic response of the silica coated Au@Ag NPs STEM in combination with EELS [ 45–48 ] was applied in a probe Cs‐corrected FEI Titan 3 transmission electron microscope (TEM). A focused electron‐beam was scanned over the NPs with a dwell time of 30 ms. At each scanning point an EEL spectrum was recorded using a Gatan Tridiem energy filter.…”

Section: Methodsmentioning

confidence: 99%

Tailoring Plasmonics of Au@Ag Nanoparticles by Silica Encapsulation

Schultz

Kirner

Potapov

et al. 2021

Advanced Optical Materials

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Hybrid metallic nanoparticles (NPs) encapsulated in oxide shells are currently intensely studied for plasmonic applications in sensing, medicine, catalysis, and photovoltaics. Here, a method for the synthesis of Au@Ag@SiO2 cubes with a uniform silica shell of variable and adjustable thickness in the nanometer range is introduced and their excellent, highly reproducible, and tunable optical response is demonstrated. Varying the silica shell thickness, the excitation energies of the single NP plasmon modes can be tuned in a broad spectral range between 2.55 and 3.25 eV. Most importantly, a strong coherent coupling of the surface plasmons is revealed at the silver–silica interface with Mie resonances at the silica–vacuum interface leading to a significant field enhancement at the encapsulated NP surface in the range of 100% at shell thicknesses t ≃ 20 nm. Consequently, the synthesis method and the field enhancement open pathways to a widespread use of silver NPs in plasmonic applications including photonic crystals and may be transferred to other non‐precious metals.

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Characterization of Nonradiative Bloch Modes in a Plasmonic Triangular Lattice by Electron Energy-Loss Spectroscopy

Cited by 4 publications

References 42 publications

Imaging of Antiferroelectric Dark Modes in an Inverted Plasmonic Lattice

Imaging of Antiferroelectric Dark Modes in an Inverted Plasmonic Lattice

Emergence of point defect states in a plasmonic crystal

Tailoring Plasmonics of Au@Ag Nanoparticles by Silica Encapsulation

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