Surface enhanced Raman scattering of molecules in metallic nanogaps

Marqués‐González, Santiago; Matsushita, Ryuji; Kiguchi, Manabu

doi:10.1088/2040-8978/17/11/114001

Cited by 22 publications

(19 citation statements)

References 75 publications

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“…Here, we report the site-selection of a 1,4-benzenedithiol (BDT) single-molecule junction by simultaneous surface-enhanced Raman spectroscopy (SERS) [24][25][26][27][28][29] and current-voltage (I-V) 30,31 measurements, at room temperature. The observed I-V response reveals the existence of three meta-stable states arising from different adsorption sites.…”

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confidence: 99%

“…To our knowledge, this is the first in situ study to the correlation between the optical and electronic properties in single-molecule junctions. The SERS signals gain intensity from two independent contributions: electromagnetic (EM) and chemical (CM) effects 25,26 . The EM effect, which is the major contributing factor, originates from local field enhancement accompanied by the excitation of localized surface plasmon resonances on metallic nanostructures.…”

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confidence: 99%

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Site-Selection in Single-Molecule Junction for Highly Reproducible Molecular Electronics

et al. 2016

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Adsorption sites of molecules critically determine the electric/photonic properties and the stability of heterogeneous molecule-metal interfaces. Then, selectivity of adsorption site is essential for development of the fields including organic electronics, catalysis, and biology. However, due to current technical limitations, site-selectivity, i.e., precise determination of the molecular adsorption site, remains a major challenge because of difficulty in precise selection of meaningful one among the sites. We have succeeded the single site-selection at a single-molecule junction by performing newly developed hybrid technique: simultaneous characterization of surface enhanced Raman scattering (SERS) and current-voltage (I-V) measurements. The I-V response of 1,4-benzenedithiol junctions reveals the existence of three metastable states arising from different adsorption sites. Notably, correlated SERS measurements show selectivity toward one of the adsorption sites: "bridge sites". This site-selectivity represents an essential step toward the reliable integration of individual molecules on metallic surfaces. Furthermore, the hybrid spectro-electric technique reveals the dependence of the SERS intensity on the strength of the molecule-metal interaction, showing the interdependence between the optical and electronic properties in single-molecule junctions.

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Site-Selection in Single-Molecule Junction for Highly Reproducible Molecular Electronics

et al. 2016

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“…It can be observed that the strongest enhancements are located at the plasmonic hotspots or the corners and edges of the octapod AuNPs, and these can be attributed to the plasmonic nanoantenna effect. [47] The simulations also indicate that the plasmonic enhancement is higher for a bi-layer (2 x 2 array) than that for monolayer or single particle arrangement. This is because there are more gaps in between the octapod Au NPs in the case of bi-layer arrangement (Fig.…”

Section: Resultsmentioning

confidence: 82%

Evolution of stellated gold nanoparticles: New conceptual insights into controlling the surface processes

et al. 2021

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Understanding the surface processes (deposition and surface diffusion) that occur at or close to the surface of growing nanoparticles is important for fabricating reproducibly stellated or branched gold nanoparticles with precise control over arm length and spatial orientation of arms around the core. By employing a simple seed-mediated strategy, we investigate the key synthetic variables for precise tuning of in situ surface processes (competition between the deposition and surface diffusion). These variables include the reduction rate of a reaction, the packing density of molecules/ions on the high surface energy facets, and temperature. As a result, the thermodynamically stabilized nanoparticles (cuboctahedron and truncated cube) and kinetic products (cube, concave cube, octapod, stellated octahedron, and rhombic dodecahedron) in different sizes with high quantitative shape yield (> 80%) can be obtained depending on the reduction rate of reaction and the packing density of molecules/ions. With computer simulation, we studied the stability of stellated (branched structure) and non-stellated (non-branched structure) gold nanoparticles at high temperature. We construct a morphology phase diagram by varying different synthetic parameters, illustrating the formation of both stellated and non-stellated gold nanoparticles in a range of reaction conditions. The stellated gold nanoparticles display shape-dependent optical properties and can be self-assembled into highly ordered superstructures to achieve an enhanced plasmonic response. Our strategy can be applied to other metal systems, allowing for the rational design of advanced new stellated metal nanoparticles with fascinating symmetry dependent plasmonic, catalytic, and electronic properties for technological applications.

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“…[1][2][3][4] At the fundamental level, it is an inelastic scattering technique that generates photons with a slightly different energy from the input. Such differences usually correspond to transitions between vibrational levels, while the electronic states stay the same.…”

Section: Introductionmentioning

confidence: 99%

Symmetry analysis of Raman scattering mediated by neighboring molecules

Williams

Andrews

2016

The Journal of Chemical Physics

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Raman spectroscopy is a key technique for the identification and structural interrogation of molecules. It generally exploits changes in vibrational state within individual molecules which produce, in the scattered light, frequencies that are absent in the incident light. Considered as a quantum optical process, each Raman scattering event involves the concurrent annihilation and creation of photons of two differing radiation modes, accompanying vibrational excitation or decay. For molecules of sufficiently high symmetry, certain transitions may be forbidden by the two-photon selection rules, such that corresponding frequency shifts may not appear in the scattered light. By further developing the theory on a formal basis detailed in other recent work [J. Chem. Phys. 144, 174304 (2016)], the present analysis now addresses cases in which expected selection rule limitations are removed as a result of the electronic interactions between neighboring molecules. In consequence, new vibrational lines may appear -even some odd parity (ungerade) vibrations may then participate in the Raman process. Subtle differences arise according to whether the input and output photon events occur at either the same or different molecules, mediated by intermolecular interactions. For closely neighboring molecules, within near-field displacement distances, it emerges that the radiant intensity of Raman scattering can have various inverse-power dependences on separation distance. A focus is given here to the newly permitted symmetries, and the results include an extended list of irreducible representations for each point group in which such behavior can arise.

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Surface enhanced Raman scattering of molecules in metallic nanogaps

Cited by 22 publications

References 75 publications

Site-Selection in Single-Molecule Junction for Highly Reproducible Molecular Electronics

Site-Selection in Single-Molecule Junction for Highly Reproducible Molecular Electronics

Evolution of stellated gold nanoparticles: New conceptual insights into controlling the surface processes

Symmetry analysis of Raman scattering mediated by neighboring molecules

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