Multipolar response of small metallic spheres: Nonlocal theory

Fuchs, Ronald; Claro, F.

doi:10.1103/physrevb.35.3722

Cited by 185 publications

(164 citation statements)

References 41 publications

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“…2,[64][65][66][67][68][69][70][71][72][73] The nonlocal hydrodynamical (NLHD) description has attracted considerable interest because of its numerical efficiency for arbitrarily-shaped objects 47,[74][75][76][77][78][79][80][81][82][83][84] and the possibility to obtain semi-analytical Example of the implementation of QCM in metallic gaps. In (a), a spatially inhomogeneous effective medium whose properties depend continuously on the separation distance is introduced in the gap between two metallic spheres.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…The non locality brings about a natural cutoff pole order: the nonlocal sphere does not polarize significantly at angular momenta higher than a certain cutoff value l c . The latter is of principal importance since it allows for a fully converged treatment of multipolar excitation effects [49]. Another important feature of the nonlocal dielectric function is that it introduces a natural cutoff angular momentum for the excitation of near-field modes [48,49], and thereby a natural cutoff for the convergence of the nonradiative decay rates.…”

Section: Size-dependent Corrections and Nonlocal Effectsmentioning

confidence: 99%

Spectroscopic properties of a two-level atom interacting with a complex spherical nanoshell

Moroz

2005

Chemical Physics

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Frequency shifts, radiative decay rates, the Ohmic loss contribution to the nonradiative decay rates, fluorescence yield, and photobleaching of a two-level atom radiating anywhere inside or outside a complex spherical nanoshell, i.e. a stratified sphere consisting of alternating silica and gold concentric spherical shells, are studied. The changes in the spectroscopic properties of an atom interacting with complex nanoshells are significantly enhanced, often more than two orders of magnitude, compared to the same atom interacting with a homogeneous dielectric sphere. The detected fluorescence intensity can be enhanced by 5 or more orders of magnitude. The changes strongly depend on the nanoshell parameters and the atom position. When an atom approaches a metal shell, decay rates are strongly enhanced yet fluorescence yield exhibits a well-known quenching. Rather contra-intuitively, the Ohmic loss contribution to the nonradiative decay rates for an atomic dipole within the silica core of larger nanoshells may be decreasing when the silica core -inner gold shell interface is approached. The quasistatic result that the radial frequency shift in a close proximity of a spherical shell interface is approximately twice as large as the tangential frequency shift appears to apply also for complex nanoshells. Significantly modified spectroscopic properties (see computer program freely available at http://www.wave-scattering.com) can be observed in a broad band comprising all (nonresonant) optical and near-infrared wavelengths.

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“…Although spatial dispersion in the permittivity of metals has been intensively studied in the past, [3][4][5][6] its experimental exploration has not been possible until very recently. Current fabrication and optical characterization techniques allow the probing of SP resonances below the nanometer, [7][8][9][10] which has renewed the theoretical interest in the nonlocal response of metallic nanostructures.…”

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confidence: 99%

Transformation-optics insight into nonlocal effects in separated nanowires

et al. 2012

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We present a transformation-optics approach which sheds analytical insight into the impact that spatial dispersion has on the optical response of separated dimers of metallic nanowires. We show that nonlocal effects are apparent at interparticle distances one order of magnitude larger than the longitudinal plasmon decay length, which coincides with the spatial regime where electron tunneling phenomena occur. Our method also clarifies the interplay between nonlocal and radiation effects taking place in the nanostructure, yielding the dimer dimensions that optimize its light harvesting capabilities. The impact of spatial nonlocality in the optical properties of metal nanoparticles is currently attracting great research attention. The presence of subnanometric geometric features in these nanostructures enables them to support extremely localized surface plasmon (SP) resonances. Classical electrodynamics predicts that the focusing ability of SPs is pushed to its maximum efficiency at these diminutive decorations, 1 where the extent of the electromagnetic fields become comparable to the Coulomb screening length ( ∼ 0.1 nm for noble metals). However, the local constitutive relations of macroscopic Maxwell's equations do not reflect the occurrence of significant electron-electron interactions in this spatial regime. Thus, a nonlocal treatment of the dielectric characteristics of metals, 2 beyond the free-electron Drude model, is required to clarify the limitations and guide the optimization of plasmonic devices.Although spatial dispersion in the permittivity of metals has been intensively studied in the past, 3-6 its experimental exploration has not been possible until very recently. Current fabrication and optical characterization techniques allow the probing of SP resonances below the nanometer, 7-10 which has renewed the theoretical interest in the nonlocal response of metallic nanostructures.11-13 Nanoparticle dimers are probably the system most thoroughly investigated in this context. [14][15][16] In this Rapid Communication, we revisit this geometry using a quasianalytical transformation-optics (TO) approach, 17 which was first developed within the local approximation.18-21 Lately, this method has been used to describe nonlocal effects in touching nanowires. 22 Here, we extend this TO framework to separated dimers, clarifying how spatial dispersion affects the light harvesting properties of these devices. Figure 1(a) depicts a pair of metal nanowires of radius R separated by a gap distance d, illuminated by an electric field polarized along the dimer axis. Under the logarithmic transformation indicated, the dimer maps into the metalinsulator-metal structure shown in Fig. 1(b). 18 The incident electric field maps into an array of dipole sources located at x = 0 with period 2π . The transformed parameters can be expressed in terms of the original ones as g = 4R √ ρ(1 + ρ) and a = 2 ln(is the relative gap size. The permittivity tensor of the dimer is described using the hydrodynamical model.2 Thus, the transverse co...

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Multipolar response of small metallic spheres: Nonlocal theory

Cited by 185 publications

References 41 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

Spectroscopic properties of a two-level atom interacting with a complex spherical nanoshell

Transformation-optics insight into nonlocal effects in separated nanowires

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