Anomalously Large Spectral Shifts near the Quantum Tunnelling Limit in Plasmonic Rulers with Subatomic Resolution

Readman, Charlie; Nijs, Bart de; Szabó, István; Demetriadou, Angela; Greenhalgh, Ryan D.; Durkan, Colm; Rosta, Edina; Scherman, Oren A.; Baumberg, Jeremy J.

doi:10.1021/acs.nanolett.9b00199

Cited by 39 publications

(61 citation statements)

References 85 publications

(348 reference statements)

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“…[22] Nanogaps provide high enhancement but are also extraordinarily sensitive to even slight variations in size. [23,24] Increasing a 1 nm gap by just 1.7 Å (the radius of one gold atom) affects the field enhancement more than varying the diameter of 60 nm AuNPs by 10 nm (Figure 1b). This potential source of variance can be avoided by using a molecular spacer such as CB[n], which binds AuNPs with a fixed interparticle spacing of 0.9 nm [25] (Figure 1a).…”

Section: Resultsmentioning

confidence: 99%

Eliminating irreproducibility in SERS substrates

Grys

Chikkaraddy

Kamp

et al. 2020

J Raman Spectroscopy

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Irreproducibility in surface-enhanced Raman spectroscopy (SERS) due to variability among substrates is a source of recurrent debate within the field. It is regarded as a major hurdle towards the widespread adoption of SERS as a sensing platform. Most of the literature focused on developing substrates for various applications considers reproducibility of lower importance. Here, we address and analyse the sources of this irreproducibility in order to show how these can be minimised. We apply our findings to a simple substrate demonstrating reproducible SERS measurements with relative standard deviations well below 1% between different batches and days. Identifying the sources of irreproducibility and understanding how to reduce these can aid in the transition of SERS from the lab to real-world applications.

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Section: Resultsmentioning

confidence: 99%

Eliminating irreproducibility in SERS substrates

Grys

Chikkaraddy

Kamp

et al. 2020

J Raman Spectroscopy

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“…A selfassembled monolayer (SAM) of analytes on the mirror surface precisely controls the size of the nanogaps and ensures that analytes are positioned at the center of the hot spots. Spacer layers are not limited to SAMs but can also consist of twodimensional (2D) materials (23,24), lipids (25), and rigid molecular scaffolding (26,27). This geometry facilitates the probing of billions of optically accessible nanojunctions with nearly identical nanogaps (17,(24)(25)(26)(27)(28)(29)(30)(31).…”

Section: Superefficient Plasmonic Nanoarchitectures For Raman Kineticmentioning

confidence: 99%

Cascaded nanooptics to probe microsecond atomic-scale phenomena

Kamp

Nijs

Kongsuwan

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Plasmonic nanostructures can focus light far below the diffraction limit, and the nearly thousandfold field enhancements obtained routinely enable few- and single-molecule detection. However, for processes happening on the molecular scale to be tracked with any relevant time resolution, the emission strengths need to be well beyond what current plasmonic devices provide. Here, we develop hybrid nanostructures incorporating both refractive and plasmonic optics, by creating SiO2nanospheres fused to plasmonic nanojunctions. Drastic improvements in Raman efficiencies are consistently achieved, with (single-wavelength) emissions reaching 107counts⋅mW−1⋅s−1and 5 × 105counts∙mW−1∙s−1∙molecule−1, for enhancement factors >1011. We demonstrate that such high efficiencies indeed enable tracking of single gold atoms and molecules with 17-µs time resolution, more than a thousandfold improvement over conventional high-performance plasmonic devices. Moreover, the obtained (integrated) megahertz count rates rival (even exceed) those of luminescent sources such as single-dye molecules and quantum dots, without bleaching or blinking.

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“…We therefore attribute the residual heterogeneity to small differences in the nanoparticle−film gap size, 27,29,30,[34][35][36]45 in Figure 2. (Left) Typical measured scattering spectrum (red circles) for a 100 nm particle on a 45 nm thick film, with a spacer of 5 nm.…”

Section: Articlementioning

confidence: 99%

Effect of Film Thickness on the Far- and Near-Field Optical Response of Nanoparticle-on-Film Systems

Armstrong¹,

Liempt²,

Zijlstra

2019

Preprint

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<p>We study the near-field and far-field optical response of nanoparticle-on-film systems using single-nanoparticle spectroscopy and numerical simulations. We find that the optical spectra contain three dominant modes - a transverse dipole and quadrupole mode, and a dominant vertical antenna mode. We vary the thickness of the metal film from 10 – 45 nm, and find that the vertical antenna mode wavelength is nearly independent of the film thickness. In contrast, we find that the associated near-field enhancement in the gap between the particle and the film strongly depends on the film thickness. This trend is also observed in the far-field where the vertical antenna mode strongly increases in amplitude for increasing film-thicknesses up to the skin depth of gold. These findings are in good agreement with a numerical model and pave the way to study field-mediated processes such as fluorescence, SERS, and localized chemistry at the same resonance wavelength but at varying degrees of field enhancement.</p>

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Anomalously Large Spectral Shifts near the Quantum Tunnelling Limit in Plasmonic Rulers with Subatomic Resolution

Cited by 39 publications

References 85 publications

Eliminating irreproducibility in SERS substrates

Eliminating irreproducibility in SERS substrates

Cascaded nanooptics to probe microsecond atomic-scale phenomena

Effect of Film Thickness on the Far- and Near-Field Optical Response of Nanoparticle-on-Film Systems

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