Plasmon Hybridization in Nanoparticle Dimers

Nordlander, Peter; Oubre, Chris; Prodan, Emil; Li, K.; Stockman, Mark I.

doi:10.1021/nl049681c

Cited by 1,605 publications

(1,808 citation statements)

References 26 publications

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“…21,118,119 We show the extinction spectra and near-eld enhancement at the gap of the Au dimer for several representative separation distances in Fig. 6(a) and 7(a), respectively.…”

Section: Faraday Discussion Papermentioning

confidence: 99%

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

et al. 2015

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(2015). A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations. Faraday Discussions, 178, The optical response of plasmonic nanogaps is challenging to address when the separation between the two nanoparticles forming the gap is reduced to a few nanometers or even subnanometer distances. We have compared results of the plasmon response within different levels of approximation, and identified a classical local regime, a nonlocal regime and a quantum regime of interaction. For separations of a fewÅngstroms, in the quantum regime, optical tunneling can occur, strongly modifying the optics of the nanogap. We have considered a classical effective model, so called Quantum Corrected Model (QCM), that has been introduced to correctly describe the main features of optical transport in plasmonic nanogaps. The basics of this model are explained in detail, and its implementation is extended to include nonlocal effects and address practical situations involving different materials and temperatures of operation.

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“…21,118,119 We show the extinction spectra and near-eld enhancement at the gap of the Au dimer for several representative separation distances in Fig. 6(a) and 7(a), respectively.…”

Section: Faraday Discussion Papermentioning

confidence: 99%

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

et al. 2015

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“…Various applications of nanoantennas have been proposed and experimentally demonstrated, including enhanced single-emitter fluorescence [13][14][15], enhanced Raman scattering [16,17], near-field polarization engineering [18][19][20], high-harmonic generation [21,22], as well as applications in integrated optical nanocircuitry [23,24]. The longitudinal resonances of a symmetric dipole antenna can be understood in terms of hybridization of the longitudinal resonances of individual antenna arms, caused by the coupling over the narrow feedgap [25,26]. Such coupling causes a mode splitting into a lower-energy "bonding" mode and a higher-energy "antibonding" mode, respectively (Fig.…”

Section: Introductionmentioning

confidence: 99%

Mode Imaging and Selection in Strongly Coupled Nanoantennas

et al. 2010

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The number of eigenmodes in plasmonic nanostructures increases with complexity due to mode hybridization, raising the need for efficient mode characterization and selection. Here we experimentally demonstrate direct imaging and selective excitation of the "bonding" and "antibonding" plasmon mode in symmetric dipole nanoantennas using confocal two-photon photoluminescence mapping. Excitation of a high-qualityfactor antibonding resonance manifests itself as a two-lobed pattern instead of the single spot observed for the broad "bonding" resonance, in accordance with numerical simulations. The two-lobed pattern is observed due to the fact that excitation of the antibonding mode is forbidden for symmetric excitation at the feedgap, while concomitantly the mode energy splitting is large enough to suppress excitation of the "bonding" mode. The controlled excitation of modes in strongly coupled plasmonic nanostructures is mandatory for efficient sensors, in coherent control as well as for implementing well-defined functionalities in complex plasmonic devices. IntroductionPlasmonic nanostructures consisting of particular arrangements of closely spaced resonant particles are of great interest since they offer a variety of eigenmodes that evolve due to mode hybridization [1]. Characterization and well-defined excitation of such eigenmodes is important in order to achieve welldefined functionality in devices [2,3] and to successfully apply techniques of coherent control [4][5][6][7]. Nanoantennas consisting of two strongly coupled particles can serve as a model system to study the impact of mode selectivity [6,8,9]. Upon illumination nanoantennas confine and enhance optical fields [10,11] and can therefore be used to tailor the interaction of light with nanomatter [12]. Various applications of nanoantennas have been proposed and experimentally demonstrated, including enhanced single-emitter fluorescence [13][14][15], enhanced Raman scattering [16,17], near-field polarization engineering [18][19][20], high-harmonic generation [21,22], as well as applications in integrated optical nanocircuitry [23,24]. The longitudinal resonances of a symmetric dipole antenna can be understood in terms of hybridization of the longitudinal resonances of individual antenna arms, caused by the coupling over the narrow feedgap [25,26]. Such coupling causes a mode splitting into a lower-energy "bonding" mode and a higher-energy "antibonding" mode, respectively (Fig. 1). Limited by the uncertainty of conventional nanofabrication, it is often difficult to fabricate antenna arrays with a reproducible gap size below 20 nm, which is necessary to achieve significant energy splitting between the bonding and the antibonding mode. As a result, the existence of the antibonding antenna resonance has hardly been considered, although it may offer interesting opportunities, such as impedance tunability, a high quality factor due to its weakly radiative nature, the launching of propagating plasmon modes with increased propagation lengths [27] and spatial select...

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“…It must be stressed that both external far-field light and electron beams can excite bright plasmon modes when these have sizable dipole moments, but only electrons can excite higher-order dark modes, and weak-dipole modes (gray modes), which couple weakly to external light, but are efficiently reacting to the evanescent electromagnetic field of the electron beams. 21,22,31,32 The requirement for electron transparent samples typically below 150 nm thickness and an expensive electron detection system are the main disadvantages of EELS. Alternatively, cathodoluminescence (CL), combined with scanning electron microscopy (SEM), circumvents these disadvantages and has been successfully used to spectrally resolve and spatially image SPs on metallic nanostructures.…”

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confidence: 99%

Plasmon Spectroscopy and Imaging of Individual Gold Nanodecahedra: A Combined Optical Microscopy, Cathodoluminescence, and Electron Energy-Loss Spectroscopy Study

Myroshnychenko¹,

et al. 2012

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Imaging localized plasmon modes in noblemetal nanoparticles is of fundamental importance for applications such as ultrasensitive molecular detection. Here, we demonstrate the combined use of optical dark-field microscopy (DFM), cathodoluminescence (CL), and electron energy-loss spectroscopy (EELS) to study localized surface plasmons on individual gold nanodecahedra. By exciting surface plasmons with either external light or an electron beam, we experimentally resolve a prominent dipole-active plasmon band in the far-field radiation acquired via DFM and CL, whereas EELS reveals an additional plasmon mode associated with a weak dipole moment. We present measured spectra and intensity maps of plasmon modes in individual nanodecahedra in excellent agreement with boundary-element method simulations, including the effect of the substrate. A simple tight-binding model is formulated to successfully explain the rich plasmon structure in these particles encompasing bright and dark modes, which we predict to be fully observable in less lossy silver decahedra. Our work provides useful insight into the complex nature of plasmon resonances in nanoparticles with pentagonal symmetry. KEYWORDS: Localized plasmons, gold nanodecahedra, dark-field microscopy and spectroscopy, cathodoluminescence spectral imaging, electron energy-loss spectroscopy, boundary-element method L ight-matter interaction at the nanoscale has attracted much attention during the past decade because of its scientific and practical relevance. In particular, an impressive amount of work on metal nanoparticles has been triggered by their ability to host localized surface plasmons (SPs), which are quantized collective oscillations of conduction electrons mediated by their coulomb interaction. 1 These excitations can be tailored over a broad spectral range by controlling the size, morphology, and composition of the particles. 1−5 In particular, plasmons in noble metal nanocrystals oscillate at frequencies within the visible and near-infrared (vis-NIR), that is, the spectral ranges of interest for optical engineering, spectroscopy, and microscopy. Actually, SPs couple efficiently to external electromagnetic radiation, 6,7 thus offering a convenient way of concentrating and enhancing the electromagnetic field intensity around nanoparticle volumes well below the light diffraction limit. These unique properties of nanoparticle plasmons play a leading role in a wide range of applications such as waveguiding 8−11 and light manipulation at the nanoscale, 12 optical trapping, 13 enhanced fluorescence, 14 single-molecule detection, and surface-enhanced Raman scattering (SERS). 15−18 Experimental access to the electromagnetic field distribution associated with nanoparticle SPs, with a sufficient degree of energy and spatial resolution, is of major importance in the

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Plasmon Hybridization in Nanoparticle Dimers

Cited by 1,605 publications

References 26 publications

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

Mode Imaging and Selection in Strongly Coupled Nanoantennas

Plasmon Spectroscopy and Imaging of Individual Gold Nanodecahedra: A Combined Optical Microscopy, Cathodoluminescence, and Electron Energy-Loss Spectroscopy Study

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