Visualizing surface plasmons with photons, photoelectrons, and electrons

El‐Khoury, Patrick Z.; Abellán, Patricia; Gong, Yu; Hage, F.; Cottom, Joshua W.; Joly, Alan G.; Brydson, Rik; Ramasse, Quentin M.; Hess, Wayne P.

doi:10.1039/c6an00308g

Cited by 21 publications

(21 citation statements)

References 70 publications

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“…As a common trend, the nanoparticle shrinking blueshifts the LSPR, while shape effects may lead to anisotropic properties (elongated structures), observation of higher order (HO) plasmonic modes or plasmon hybridization (when dealing with hollow systems or cavities) . Additionally, it must be pointed out that the resonance energy may be also dependent on the excitation source, meaning that discrepancies between photon and electron excitations may be taken into account . Regardless of this facts, the measured energy of the LSPR, centered at 4.12 eV in the example shown in Figure , is in agreement with the experimental values reported by other authors through different techniques, mainly based on ellipsometry measurements where both, the size and the shape dependence of the LSPR are reported.…”

supporting

confidence: 80%

High Spatial Resolution Mapping of Localized Surface Plasmon Resonances in Single Gallium Nanoparticles

Mata

Catalán‐Gómez

Nucciarelli

et al. 2019

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materials, as certain semiconductor systems, [6] have been demonstrated to show plasmonic behavior, where the plasmon resonance is achieved by the excitation of interband transitions. [7] Among metals, noble metals as gold and silver have been the most extensively studied and exploited plasmonic systems, whose response lies on the VIS-IR spectral region. However, expanding the operability range up to the UV region is highly desirable to cover further applications, [8] which requires exploring alternative plasmonic materials.Within this context, few material systems optically active at the UV, as Mg, Al, or Ga are currently catching the attention of many research groups. [9,10] The ability to obtain these materials as colloidal suspensions offers a further advantage since it allows for their easy and cheap synthesis as nanostructures. Aluminum is an attractive choice as UV plasmonic material due to its bulk plasma frequency (15 eV) and earth abundance. [11] The strong interband transitions in Al, at about 1.5 eV, damp the possible resonances at that spectral range (NIR), while the material can support LSPR below and above that region. The short wavelengths of Al resonances (typically, 150-250 nm) become comparable to the nanoparticle (NP) size, leading to the emergence of higher order LSPRs. Regarding the spectral shape, the large linewidth of Al resonances as compared to noble metals can be understood through the modified long wavelength approximation, where the radiative damping scales with the cubed oscillation frequency (ω 3 ). [12] Although much less studied until date, Mg also shows UV plasmon resonances as consequence of its bulk plasma frequency, supporting IR resonances, too, in contrast to Al. Up to three different LSPR modes have been reported for Mg hexagonal nanoplates. [9] Another alternative UV plasmonic material is gallium (Ga), having a high bulk plasmon energy, at 14 eV; [13] exhibiting strong UV LSPR due to its negative real part of the electric function along with its low imaginary part of the dielectric function. Simple synthetic procedures allow obtaining gallium nanoparticles (Ga NPs) in a cost effective way such as thermal evaporation. The plasmonic response of the synthesized Ga NPs can be tuned, for instance, as function of their size and shape. [14][15][16] Thus, Ga NPs are among the ideal candidates to spread the application range of plasmonic systems suitable, for instance, for DNA sensing. [17] Plasmonics has emerged as an attractive field driving the development of optical systems in order to control and exploit light-matter interactions. The increasing interest around plasmonic systems is pushing the research of alternative plasmonic materials, spreading the operability range from IR to UV. Within this context, gallium appears as an ideal candidate, potentially active within a broad spectral range (UV-VIS-IR), whose optical properties are scarcely reported. Importantly, the smart design of active plasmonic materials requires their characterization at high spatial and spectral resolu...

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supporting

confidence: 80%

High Spatial Resolution Mapping of Localized Surface Plasmon Resonances in Single Gallium Nanoparticles

Mata

Catalán‐Gómez

Nucciarelli

et al. 2019

Small

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“…In EELS inside a scanning transmission electron microscope (STEM) a high-energy monochromatic electron beam (60-300 keV) passes through or near (aloof mode) the structure of interest, and the energy spectrum resulting from interactions is measured. [29] EELS can probe a wide range of excitations, including phonons at tens to hundreds of meV, [30] various plasmon types (localized, surface and bulk) as well as interband transitions in the eV range, [31] and the ionization edges of electron shells (10-1000 eV region). With new advances in monochromatic electron sources, the energy resolution of STEM-EELS can reach down to 10 meV whilst retaining sub-angstrom spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Electron Energy Loss Spectroscopy of Bright and Dark Modes in Hyperbolic Metamaterial Nanostructures

Isoniemi

Maccaferri

Ramasse

et al. 2020

Advanced Optical Materials

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Layered metal/dielectric hyperbolic metamaterials (HMMs) support a wide landscape of plasmon polariton excitations. In addition to surface plasmon polaritons, coupled Bloch-like gap-plasmon polaritons with high modal confinement inside the multilayer are supported.Photons can excite only a subset of these polaritonic modes, typically with a limited energy and momentum range in respect to the wide set of high-K modes supported by hyperbolic dispersion media, and coupling with gratings or local excitation is necessary. Strikingly, electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope allows nm-scale local excitation and mapping of the spatial field distribution of all the modes supported by a photonic or plasmonic structure, both bright and dark, and also all other inelastic interactions of the beam, including phonons and interband transitions. Herein, experimental evidence of the spatial distribution of plasmon polaritons in multilayered type II 2 HMM nanostructures is acquired with an aloof electron beam adjacent to structures of current interest. HMM pillars are useful for their separation and adjustability of optical scattering and absorption, while HMM slot cavities can be used as waveguides with high field confinement.The nature of the modes is confirmed with corresponding simulations of EEL and optical spectra and near-field intensities.

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“…We first provide a comparative review of electronbased and photon-based techniques, which have already been the focus of several reviews [10][11][12][13] and research papers [14,15], and proceed back to the roots of plasmonics, which dates in the 1950s, where the concepts of local and nonlocal phenomena were first proposed. Within the two classes of tools just described, we then juxtapose four groups of techniques, based on their excitation (i.e., pumping) and detection (i.e., probing) mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Multipolar and bulk modes: fundamentals of single-particle plasmonics through the advances in electron and photon techniques

2020

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Recent developments in the application of plasmonic nanoparticles have showcased the importance of understanding in detail their plasmonic resonances at the single-particle level. These resonances can be excited and probed through various methods, which can be grouped in four categories, depending on whether excitation and detection involve electrons (electron energy loss spectroscopy), photons (e.g., dark-field microscopy), or both (cathodoluminescence and photon-induced near-field electron microscopy). While both photon-based and electron-based methods have made great strides toward deepening our understanding of known plasmonic properties and discovering new ones, they have in general progressed in parallel, without much cross-pollination. This evolution can be primarily attributed to the different theoretical approaches driving these techniques, mainly dictated by the inherent different nature of electrons and photons. The discrepancies that still exist among them have hampered the development of a holistic approach to the characterization of plasmonic materials. In this review therefore, we aim to briefly present those electron-based and photon-based methods fundamental to the study of plasmonic properties at the single-particle level, with an eye to new behaviors involving multipolar, propagating, and bulk modes coexisting in colloidal nanostructures. By exploring the key fundamental discoveries in nanoparticle plasmonics achieved with these techniques, herein we assess how integrating this information could encourage the creation of a unified understanding of the various phenomena occurring in individual nanoparticles, which would benefit the plasmonics and electron microscopy communities alike.

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Visualizing surface plasmons with photons, photoelectrons, and electrons

Cited by 21 publications

References 70 publications

High Spatial Resolution Mapping of Localized Surface Plasmon Resonances in Single Gallium Nanoparticles

High Spatial Resolution Mapping of Localized Surface Plasmon Resonances in Single Gallium Nanoparticles

Electron Energy Loss Spectroscopy of Bright and Dark Modes in Hyperbolic Metamaterial Nanostructures

Multipolar and bulk modes: fundamentals of single-particle plasmonics through the advances in electron and photon techniques

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