Theory of Optical Excitation of Plasmons in Metals

Melnyk, Andrew R.; Harrison, Michael J.

doi:10.1103/physrevb.2.835

Cited by 224 publications

(103 citation statements)

References 25 publications

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“…First, the bulk dielectric function is modified, since the electronic mean free path is then shorter than in the bulk [45]. Second, nonlocal effects come into play [46,47,48]. The first effect can easily be incorporated by replacing the bulk dielectric function ε B (ω) with its size-dependent modification…”

Section: Size-dependent Corrections and Nonlocal Effectsmentioning

confidence: 99%

“…For simple Drude theory and isotropic scattering one usually takes A = 1. On the other hand, nonlocal effects, i.e., when the Fourier transform of the dielectric function depends in addition to ω also on k, are associated with the resonant excitation of longitudinal bulk plasmon modes (either propagating ones, with frequency above the plasma frequency ω p , or evanescent ones, with frequency below the plasma frequency ω p ) [46,47,48]. The neglect of the nonlocal responses of the substrate is the main reason why a phenomenological treatment will generally break down when the radiating atom is very close (within a few nanometers) to the sphere surface [48].…”

Section: Size-dependent Corrections and Nonlocal Effectsmentioning

confidence: 99%

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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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Section: Size-dependent Corrections and Nonlocal Effectsmentioning

confidence: 99%

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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“…When metal nanoparticles are exposed to light on resonance with their absorption wavelength, a collective oscillation of electrons in the conduction band takes place [13,14]. This creates a charge separation with respect to the lattice [2,15].…”

Section: Localized Surface Plasmon Resonance (Lspr) and Mie Theorymentioning

confidence: 99%

“…In this case the facet energies of the hexagonal close packed (HCP) structure of the cobalt template are known to increase 0001 < 10-10 < 10-11 < 11-20 < 10-12 < 11-21 with respective energies of 131,140,149,155,156,163 (meV/Å 2 ) [109]. This means that the oxidation and generation of Kirkendall voids were initiated on the [11][12][13][14][15][16][17][18][19][20][21] plane of the cobalt lattice.…”

Section: Tuning the Lspr Of Hgnsmentioning

confidence: 99%

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

2016

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By electrodeposition and galvanic replacement reaction, we developed a facile, time-saving, cost-effective, and environmentally friendly, two-step synthesis route to obtain a controllable cobalt oxide/Au hierarchically nanostructured electrode for glucose sensing. The nanomaterials were characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, energy-dispersive spectrometry, and X-ray photoelectron spectroscopy, meanwhile, the sensing performance was investigated by cyclic voltammetry and amperometric response. The results revealed that this novel electrode exhibited excellent electrocatalytic performance toward glucose oxidation, with a wide double-linear range from 0.2 μM to 20 mM and a low detection limit of 0.1 μM based on a signal-to-noise ratio of 3, which was mainly attributed to the ability of loading a small amount of Au with good electron conductivity on the surface of cobalt oxide nanosheets with large active surface area and synergistic electrocatalytic activity of Au and cobalt oxide toward glucose electrooxidation. This facile, sensitive, and selective glucose sensor is also proven to be suitable for the detection of glucose in human serum.

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“…Thus a rigorous theoretical study on the SE rate and OQE of emitters in nanoscale structure is desirable for getting a better physical understanding and optimal design of the nano-structure to achieve high-efficiency fluorescence. In this paper, the SE rates and EQE of emitters in a spherical NP with and without a silver nanoshell are rigorously investigated through a classical electromagnetic approach with the consideration of the nonlocal effect of the silver nanoshell [14][15]. Different from the SE rate in a dielectric particle with a diameter around several wavelengths [16], the SE rate in a NP with a diameter below 100nm is considerably slower than that in free space by almost an order of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Enhanced efficiency of a fluorescing nanoparticle with a silver shell

Choy

Chen

2009

J. Phys.: Conf. Ser.

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Abstract. Spontaneous emission (SE) rate and the fluorescence efficiency of a bare fluorescing nanoparticle (NP) and the NP with a silver nanoshell are analyzed rigorously by using a classical electromagnetic approach with the consideration of the nonlocal effect of the silver nano-shell. The dependences of the SE rate and the fluorescence efficiency on the core-shell structure are carefully studied and the physical interpretations of the results are addressed. The results show that the SE rate of a bare NP is much slower than that in the infinite medium by almost an order of magnitude and consequently the fluorescence efficiency is usually low. However, by encapsulating the NP with a silver shell, highly efficient fluorescence can be achieved as a result of a large Purcell enhancement and high out-coupling efficiency (OQE) for a well-designed core-shell structure. We also show that a higher SE rate may not offer a larger fluorescence efficiency since the fluorescence efficiency not only depends on the internal quantum yield but also the OQE. IntroductionFluorescent nanomaterials have been the subject of intensive research in recent years for their vast applications ranging from biomedical therapeutics and diagnostics to information storage and optoelectronics [1][2][3]. For fluorescence based applications, fluorescence efficiency, i.e. the external quantum efficiency (EQE) of the emitter, is an important issue. Due to the existence of pronounced nonradiative decay of excitons in the nanoscale structure, low EQE is an often-observed feature. Most of the strategies so far employed aim to reduce the nonradiative decay rate [4][5][6] for improving the fluorescence efficiency. The direct and effective approach to improve EQE is to increase radiative decay rate [7] and out-coupling efficiency (OQE) since EQE is the product of internal quantum yield (i.e. internal quantum efficiency) (IQE) and OQE. The enhancement of radiative decay rate results in the Purcell enhancement of IQE [8,9]. Here, we will address this issue. The radiative decay rate, i.e. spontaneous emission (SE) rate, can be enhanced by utilizing the surface plasmon effect [10][11][12] or the microcavity effect [13]. According to the near field nature of surface plasmon, the SE rate in a dielectric nanoparticle (NP) encapsulated with a metallic shell can be greatly enhanced. However, the metallic shell introduces extra absorption loss and may result in a small OQE. Consequently, fluorescence efficiency may still be low although the SE rate is greatly enhanced. Thus a rigorous theoretical study on the SE rate and OQE of emitters in nanoscale structure is desirable for getting a better physical understanding and optimal design of the nano-structure to

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Theory of Optical Excitation of Plasmons in Metals

Cited by 224 publications

References 25 publications

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

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

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

Enhanced efficiency of a fluorescing nanoparticle with a silver shell

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