Tuning localized plasmons in nanostructured substrates for surface-enhanced Raman scattering

Perney, N.M.B.; Baumberg, Jeremy J.; Zoorob, M.E.; Charlton, Martin D. B.; Mahnkopf, S.; Netti, Caterina

doi:10.1364/opex.14.000847

Cited by 237 publications

(242 citation statements)

References 14 publications

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“…13 Here, we map the entire plasmon landscape, moving between regimes where the incident optical wavelength is both much larger and much smaller than the void feature size. In order …”

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confidence: 99%

Tuning localized plasmon cavities for optimized surface-enhanced Raman scattering

et al. 2007

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Mesostructured metallic substrates composed of square pyramidal pits are shown to confine localized plasmons. Plasmon frequency tuning is demonstrated using white light reflection spectroscopy with a wide range of structure dimensions from 400 to 3000 nm. Using a simple plasmon cavity model, we demonstrate how the individual pit morphology and not their periodicity controls the resonance frequencies. By measuring the surface-enhanced Raman scattering ͑SERS͒ signals from monolayers of benzenethiol on the same range of mesostructures, we extract a quantitative connection between absorption, field enhancement, and SERS signals. The match between theory and experiment enables effective design of plasmon devices tailored for particular applications, such as optimizing SERS substrates. DOI: 10.1103/PhysRevB.76.035426 PACS number͑s͒: 73.20.Mf, 42.70.Qs, 72.15.Rn, 81.07.Ϫb Raman scattering is a crucial spectroscopic technique for identifying molecules through their vibrational resonances and has increasingly important applications in monitoring low concentrations of impurities or trace biomolecules.1-3 It has also been suggested for direct monitoring of coupling of molecular distortions and electronic transport in molecular electronics. [4][5][6] However, the terribly weak Raman cross section has always made such application problematic. The enormous enhancement in cross section when the molecules are held close to a metal surface with nanoscale roughness 7,8 has driven the hope that surface-enhanced Raman scattering ͑SERS͒ will become a viable and reproducible diagnostic. While improvements have been made in terms of enhancement factor, reproducibility, and in understanding that plasmons underpin such enhancements, 9 it is unclear how to precisely design nanostructures to optimize the Raman signatures. Over the last five years, we have shown that mesostructured metal films comprised of arrays of voids form excellent surfaces for localizing plasmons while retaining strong coupling to external light.10-13 Recently, we showed, using angularly resolved SERS on such void substrates, that incident photons are transducted both into and out of molecules via plasmons, 14 giving hope that reproducible substrates can be designed for specific applications. While most SERS research has focused on using the nanoscale junctions between metallic particles such as colloids 15 or lithographic arrays 16 that have broad plasmon resonances which can only be tuned through control of shape anisotropy or gap dimensions, the voids show strong sharp tunable plasmon resonances. Previous work has shown that optimized samples possess plasmon absorption that lies between the laser wavelength and outscattered Raman emission; 17-19 however, they are unable to make clear the quantitative link between plasmon resonant absorption and SERS emission.In this paper, we present calibrated spectroscopic measurements on systematically engineered plasmonic mesostructured metal surfaces. We show the quantitative connection between the resonance arising from ...

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“…13 Here, we map the entire plasmon landscape, moving between regimes where the incident optical wavelength is both much larger and much smaller than the void feature size. In order …”

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confidence: 99%

Tuning localized plasmon cavities for optimized surface-enhanced Raman scattering

et al. 2007

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“…[ 5 ] These are not only expensive and time consuming but are also often cumbersome and require precise integration of multistep processes, thus limiting the scalability of the resulting structures. For instance, while photolithography [ 6 ] is a fl exible method for generating optical patterns, it is limited by the optical diffraction limit and is essentially 2D, meaning that many steps must be iterated to create a 3D structure.…”

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confidence: 99%

Hierarchical Electrohydrodynamic Structures for Surface‐Enhanced Raman Scattering

2012

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Surface enhanced Raman scattering (SERS) is a well‐established spectroscopic technique that requires nanoscale metal structures to achieve high signal sensitivity. While most SERS substrates are manufactured by conventional lithographic methods, the development of a cost‐effective approach to create nanostructured surfaces is a much sought‐after goal in the SERS community. Here, a method is established to create controlled, self‐organized, hierarchical nanostructures using electrohydrodynamic (HEHD) instabilities. The created structures are readily fine‐tuned, which is an important requirement for optimizing SERS to obtain the highest enhancements. HEHD pattern formation enables the fabrication of multiscale 3D structured arrays as SERS‐active platforms. Importantly, each of the HEHD‐patterned individual structural units yield a considerable SERS enhancement. This enables each single unit to function as an isolated sensor. Each of the formed structures can be effectively tuned and tailored to provide high SERS enhancement, while arising from different HEHD morphologies. The HEHD fabrication of sub‐micrometer architectures is straightforward and robust, providing an elegant route for high‐throughput biological and chemical sensing.

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“…The unique property of the pyramidal structure is claimed to be responsible for controlling the propagating surface plasmons, which provides a hot spot for remarkably enhanced and uniform SERS intensity [21,22]. As a result, this sparked concerted efforts by a number of researchers to utilize Klarite design as a starting point towards the fabrication of idealized SERS substrate.…”

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confidence: 99%

Self-Assembled Plasmonic Pyramids from Anisotropic Nanoparticles for High-Efficient SERS

et al. 2017

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Surface-enhanced Raman scattering (SERS) substrates play important roles for the enhancement of inelastic scattering signals. Traditional substrates such as roughened electrodes and colloidal aggregates suffer from well-known signal reproducibility issues, whereas for current dominant two-dimensional planar systems, the hot spot distributions are limited by the zero-, one-or two-dimensional plane. The introduction of a three-dimensional (3D) system such as a pyramid geometry breaks the limitation of a single Cartesian SERS-active area and extends it into the z-direction, with the tip potentially offering additional benefits of strong field enhancement and high sensitivity. However, current 3D pyramidal designs are restricted to film deposition on prepared pyramid templates or self-assembly in pyramidal molds with spherical building blocks, hence limiting their SERS effectiveness. Here, we report on the fabrication of a new class of low cost and well-defined plasmonic nanoparticle pyramid arrays from different anisotropic shaped nanoparticles using combined top-down lithography and bottom-up self-assembly approach. These pyramids exhibit novel optical scattering properties that can be exploited for the design of reproducible and sensitive SERS substrate. The SERS intensity was found to decrease drastically in accordance with a power law function as the focal planes move from the apex of the pyramid structure towards the base. In comparison to sphere-based building blocks, pyramids assembled from anisotropic rhombic dodecahedral gold nanocrystals with numerous sharp tips exhibited the strongest SERS performance.Graphical Abstract Macroscale pyramidal array films with plasmonic tunability as a new class of SERS substrate for sensitive detection of chemicals.

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Tuning localized plasmons in nanostructured substrates for surface-enhanced Raman scattering

Cited by 237 publications

References 14 publications

Tuning localized plasmon cavities for optimized surface-enhanced Raman scattering

Tuning localized plasmon cavities for optimized surface-enhanced Raman scattering

Hierarchical Electrohydrodynamic Structures for Surface‐Enhanced Raman Scattering

Self-Assembled Plasmonic Pyramids from Anisotropic Nanoparticles for High-Efficient SERS

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