Preparation, Characterization, and Application of Au-Shell/Polystyrene Beads and Au-Shell/Magnetic Beads

Ji, Tianhao; Lirtsman, Vladislav; Avny, Yair; Davidov, D.

doi:10.1002/1521-4095(200108)13:16<1253::aid-adma1253>3.0.co;2-t

Cited by 172 publications

(154 citation statements)

References 12 publications

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“…Hollow Ag/Au shells can be fabricated by using silica [30] or polystyrene [31][32][33] spheres as templates. For our application, polystyrene (PS) is clearly the preferred choice as micro beads with a narrow size distribution are readily available.…”

Section: Templatingmentioning

confidence: 99%

Nanoporous Plasmonic Metamaterials

et al. 2008

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We review different routes for the generation of nanoporous metallic foams and films exhibiting well-defined pore size and short-range order. Dealloying and templating allows the generation of both two-and threedimensional structures which promise a well defined plasmonic response determined by material constituents and porosity. Viewed in the context of metamaterials, the ease of fabrication of samples covering macroscopic dimensions is highly promising, and suggests more in-depth investigations of the plasmonic and photonic properties of this material system for photonic applications.

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Section: Templatingmentioning

confidence: 99%

Nanoporous Plasmonic Metamaterials

et al. 2008

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“…It has been previously shown that extinction spectra of incomplete, highly fragmented nanoshells do not exhibit geometrical resonances [8], but are dominated instead by absorption resonances of the metal clusters on the spheres [9].…”

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confidence: 99%

“…Spectra of sparsely coated spheres as in Fig.2(a) exhibit only a single peak centered near 420nm. This is a signature of the excitation of the dipolar plasmon eigenmodes of individual, non-aggregated silver nanocrystals nucleated on the spheres [9]. Due to the dilute metal surfacecoverage, these modes do not couple to the weak Mie resonances of the dielectric spheres, and are therefore independent of sphere size.…”

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confidence: 99%

Coherent Light Scattering from Semicontinuous Silver Nanoshells near the Percolation Threshold

2006

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We report on measurements of visible extinction spectra of semicontinuous silver nanoshells grown on colloidal silica spheres. We find that thin, fractal shells below the percolation threshold exhibit geometrically tunable plasmon resonances. A modified scaling theory approach is used to model the dielectric response of such shells, which is then utilized to obtain the extinction cross section in a retarded Mie scattering formalism. We show that such spherical resonators support unique plasmon dynamics: in the visible there is a new regime of coherently driven cluster-localized plasmons, while crossover to homogeneous response in the infrared predicts a delocalized shell plasmon.Noble-metal nano-scale shells are comprised of thin gold or silver films surrounding sub-micron dielectric cores. In recent years nanometer-scale metal particles have been the focus of extensive studies, owing mainly to large enhancements of surface-induced electric fields at the plasma resonance of the nanoparticles [1]. This unique optical response is well exemplified in the nanoshells' extinction spectra, which are governed by a geometrically tunable plasmon resonance. When the core diameter is in the sub-micrometer range, the optical response of the composite particle is tunable over the entire visible and near infrared spectrum [2]. This constitutes a powerful tool for custom-designing Raman [3] and surface-plasmon-based ultra sensitive optical sensors [4].The strong optical resonance observed in spherical nanoshells is attributed to a delocalized shell plasmon, typically well-modelled by classical linear response to electromagnetic (EM) plane-wave scattering [5]. This was formulated by Aden and Kerker (AK) [6] as an extension to classical Mie scattering theory. More refined theories utilizing ab-initio quantum mechanical modelling of metallic nanoshells have also verified this approach [7].The existence of a spherical-shell plasmon relies on a symmetric and uniform shell morphology, and is typically observed in smooth, continuous nanoshells. It has been previously shown that extinction spectra of incomplete, highly fragmented nanoshells do not exhibit geometrical resonances [8], but are dominated instead by absorption resonances of the metal clusters on the spheres [9].In this Letter we present light scattering experiments of silica spheres coated with discontinuous silver nanoshells. We distinguish two shell morphologies with differing optical signatures. For thin, two-dimensional (2D) fractal shells, the optical response of the metal is best described within the framework of percolation theory. While these shells support mainly localized plasmon modes and are electrically insulating, distinct geometrical resonances are clearly present, due to coherent optical driving of cluster-localized plasmons. For thick (3D), conducting and porous shells classical, Maxwell Garnett (MG) theory is used instead to obtain the effective dielectric response of the shell. In both cases, although the shells are locally highly irregular, observed fine...

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“…Preparation of Au/TiO 2 nanorod composites and modification of BDD electrode Au/TiO 2 nanorod composites were prepared based on the literatures. [24][25][26][27] Firstly, 1 wt%, 0.6 mL HAuCl 4 solution was added into the dispersed TiO 2 nanorods suspension (40 mL, pH 1.5) under stirring vigorously and keep stirred for several hours to allow complete adsorption of negatively charged [AuCl 4 ] -ions onto the positively charged TiO 2 nanorods surface. Reduction of [AuCl 4 ] -was achieved by the dropwise addition sodium borohydride (0.5 mg mL -1 ) until a color change was observed.…”

Section: Experimental Chemicals and Apparatusmentioning

confidence: 99%

Electrochemical Detection of Catechol on Boron‐doped Diamond Electrode Modified with Au/TiO₂ Nanorod Composite

Wei

Liu

et al. 2011

J Chinese Chemical Soc

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Au/TiO 2 nanorod composites with different ratios of [TiO 2 ]: [Au] have been prepared by chemically reducing AuCl 4 -on the positively charged TiO 2 nanorods surface and used to modify boron-doped diamond (BDD) electrodes. The electrochemical behaviors of catechol on the bare and different Au/TiO 2 nanorod composites-modified BDD electrodes are studied. The cyclic voltammetric results indicate that these different Au/TiO 2 nanorod composites-modified BDD electrodes can enhance the electrocatalytic activity toward catechol detection, as compared with the bare BDD electrode. Among these different conditions, the Au/TiO 2 -BDD3 electrode (the ratio of [TiO 2 ]:[Au] is 27:1) is the most choice for catechol detection. The electrochemical response dependences of the Au/TiO 2 -BDD3 electrode on pH of solution and the applied potential are studied. The detection limit of catechol is found to be about 1.4 × 10 -6 M in a linear range from 5 × 10 -6 M to 200 × 10 -6 M on the Au/TiO 2 -BDD3 electrode.

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Preparation, Characterization, and Application of Au-Shell/Polystyrene Beads and Au-Shell/Magnetic Beads

Cited by 172 publications

References 12 publications

Nanoporous Plasmonic Metamaterials

Nanoporous Plasmonic Metamaterials

Coherent Light Scattering from Semicontinuous Silver Nanoshells near the Percolation Threshold

Electrochemical Detection of Catechol on Boron‐doped Diamond Electrode Modified with Au/TiO₂ Nanorod Composite

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Preparation, Characterization, and Application of Au-Shell/Polystyrene Beads and Au-Shell/Magnetic Beads

Cited by 172 publications

References 12 publications

Nanoporous Plasmonic Metamaterials

Nanoporous Plasmonic Metamaterials

Coherent Light Scattering from Semicontinuous Silver Nanoshells near the Percolation Threshold

Electrochemical Detection of Catechol on Boron‐doped Diamond Electrode Modified with Au/TiO2 Nanorod Composite

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Electrochemical Detection of Catechol on Boron‐doped Diamond Electrode Modified with Au/TiO₂ Nanorod Composite