Highly Stable, Protected Plasmonic Nanostructures for Tip Enhanced Raman Spectroscopy

Barrios, Carlos Angulo; Malkovskiy, Andrey V.; Kisliuk, A.; Sokolov, Alexei P.; Foster, Mark D.

doi:10.1021/jp8098126

Cited by 71 publications

(79 citation statements)

References 29 publications

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“…While there have been efforts to encapsulate and passivate Ag surfaces to retain its excellent properties, the encapsulating layer is often as thick as or thicker than the nanostructures themselves. 15,16 This poses a problem for LSPR sensing, as it relies on near-field interactions which are the strongest on the surface of the particle. 17 Among its many excellent properties enabling myriad different applications, 18−22 atomically thin graphene has been proven to be impenetrable to gas molecules as small as helium atoms.…”

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confidence: 99%

Graphene-Enabled Silver Nanoantenna Sensors

et al. 2012

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Silver is the ideal material for plasmonics because of its low loss at optical frequencies but is often replaced by a more lossy metal, gold. This is because of silver's tendency to tarnish and roughen, forming Ag(2)S on its surface, dramatically diminishing optical properties and rendering it unreliable for applications. By passivating the surface of silver nanostructures with monolayer graphene, atmospheric sulfur containing compounds are unable to penetrate the graphene to degrade the surface of the silver. Preventing this sulfidation eliminates the increased material damping and scattering losses originating from the unintentional Ag(2)S layer. Because it is atomically thin, graphene does not interfere with the ability of localized surface plasmons to interact with the environment in sensing applications. Furthermore, after 30 days graphene-passivated silver (Ag-Gr) nanoantennas exhibit a 2600% higher sensitivity over that of bare Ag nanoantennas and 2 orders of magnitude improvement in peak width endurance. By employing graphene in this manner, the excellent optical properties and large spectral range of silver can be functionally utilized in a variety of nanoscale plasmonic devices and applications.

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confidence: 99%

Graphene-Enabled Silver Nanoantenna Sensors

et al. 2012

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“…Their Raman bands, which appear around 188, 243, and 273 cm -1 for Ag 2 S and 432, 460, 595, 623, 970 (strong), and 1079 cm -1 for Ag 2 SO 4 [2], can coincide with spectral regions of interest such as the radial breathing mode of carbon nanotubes (CNT) [3]. It was also shown that the electric field enhancement decreases with the aging of the silver surface [4]; the thickness of Ag 2 S increases over time as it is not a self-limiting process confined to the surface [5]. Thus, experiments with silver probes are almost exclusively performed on the day of the probe preparation as described in previous works [6].…”

Section: Introductionmentioning

confidence: 94%

Chemical stability of plasmon-active silver tips for tip-enhanced Raman spectroscopy

Kalbacova¹,

Rodriguez²,

Desale³

et al. 2015

Nanospectroscopy

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Silver nanostructures are used in tip- and surface-enhanced Raman spectroscopy due to their high electric field enhancement over almost the entire visible spectral range. However, the low chemical stability of silver, compared to other noble metals, promotes silver sulfide and sulfate formation which decreases its plasmonic activity. This is why silver tips are usually prepared on the same day of the experiments or are disregarded in favour of gold that is chemically more stable. Since silver degradation cannot be avoided, we hypothesized that a protection layer may be able to minimize or control degradation. In this contribution, we report the successful preparation of 4-biphenylthiol and 4’-nitro-4-biphenylthiol self-assembled monolayers on silver tips in order to protect them against tarnishing and to investigate the effect on the life-time of the plasmonic activity. The electrochemically etched wire surface was probed via Raman spectroscopy and scanning electron microscopy. The best long term stability and resistance against corrosion was shown by a monolayer of 4-biphenylthiol formed from dimethylformamide which did not display any degradation of the metallic tip during the observed period. Here, we demonstrate an easy and straightforward approach towards increasing the chemical stability of silver TERS-active probes.

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“…The interested reader is referred to detailed overviews about various tip production procedures in refs. [22][23][24][25]. Electrochemically etched, pencil-shaped metal cones with a rather smooth surface seem to give the highest enhancements, but metal-coated cantilevers have also been employed in several groups.…”

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confidence: 99%

Studying Surface Chemistry beyond the Diffraction Limit: 10 Years of TERS

2010

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The use of an illuminated scanning probe tip to greatly enhance Raman scattering from the sample underneath the tip is one of the most intriguing developments in optical spectroscopy, and the steeply increasing number of publications per year shows that chemists, physicists and biologists alike recognize the importance and great potential of this technique. With tip-enhanced Raman spectroscopy (TERS), one of the main goals in surface science has been achieved, namely the combination of scanning probe microscopy and optical spectroscopy such as Raman spectroscopy. Important here is the use of the tip as an optical antenna to substantially increase the emitted radiation and to simultaneously improve the optical resolution much beyond the Abbe diffraction limit. This permits the correlation of topographic and chemical information of the same surface region. The synergy of detailed insight in morphology and the chemical nature of the target species facilitates data interpretation significantly and enables characterization of interfaces at the nanometer scale. A wide variety of substrates and sample molecules have been studied with TERS since the first publication of tip-enhanced Raman spectra, and the technique has reached a first level of maturity on its 10th birthday, with TERS applications extending into various research fields from surface chemistry over biology to nanoscale physics.

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Highly Stable, Protected Plasmonic Nanostructures for Tip Enhanced Raman Spectroscopy

Cited by 71 publications

References 29 publications

Graphene-Enabled Silver Nanoantenna Sensors

Graphene-Enabled Silver Nanoantenna Sensors

Chemical stability of plasmon-active silver tips for tip-enhanced Raman spectroscopy

Studying Surface Chemistry beyond the Diffraction Limit: 10 Years of TERS

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