High resolution scanning near field mapping of enhancement on SERS substrates: comparison with photoemission electron microscopy

Awada, Chawki; Plathier, Julien; Dab, Chahinez; Charra, Fabrice; Douillard, Ludovic; Ruediger, Andréas

doi:10.1039/c5cp08015k

Cited by 20 publications

(19 citation statements)

References 52 publications

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“…Mapping the spatial distribution of SERS enhancement within a hotspot requires a Raman probe that can be controllably placed at different positions within a hotspot with nanoscale precision. Awada et al [ 27 ] fulfilled this requirement by functionalizing a sharp gold tip with Raman active molecules (4‐NTP). The tip was scanned over a semicontinuous gold film with randomly distributed hotspots while recording the molecular SERS enhancement as a function of tip position.…”

Section: Plasmonic Hotspotsmentioning

confidence: 99%

“…[ [ 11 ] ] Raman scattering from the silicon tip (Raman shift 520 cm −1 ) reveals the local SERS enhancement without altering the local hotspot configuration as was the case for metallic tips. [ 27 ] Canonical SERS hotspots formed by plasmonic gold nanodimers were probed using this technique. The dimers consisted of two discs with a conical shape comparable with those shown in Figure 1b further below, which allowed for the silicon tip to reach inside the dimer gap for accurate mapping.…”

Section: Plasmonic Hotspotsmentioning

confidence: 99%

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Experimental tests of surface‐enhanced Raman scattering: Moving beyond the electromagnetic enhancement theory

Heeg

Mueller

Waßerroth

et al. 2020

J Raman Spectroscopy

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The electromagnetic enhancement theory describes surface‐enhanced Raman scattering (SERS) as a Raman effect that takes place in the near‐field of a plasmonic nanostructure. The theory has been very successful in explaining the fundamental properties of SERS, modelling the performance of different metals as enhancing materials and optimizing SERS hotspots for strongest possible enhancement. Over the last decade, a number of carefully designed experimental studies have examined predictions of the electromagnetic theory like the size and shape of SERS hotspots, the absolute magnitude of the enhancement and the width of the SERS resonance. Although the overall picture was quite satisfactory, the theory failed to predict key aspects of SERS, for example, the absolute magnitude of the plasmonic enhancement. We scrutinize these experiments and review them focusing on the results that require going beyond the electromagnetic enhancement theory. We argue that the results of these experiments create the need to develop the theory of SERS further, especially the exact role of plasmonic enhancement in inelastic light scattering.

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Section: Plasmonic Hotspotsmentioning

confidence: 99%

Section: Plasmonic Hotspotsmentioning

confidence: 99%

Experimental tests of surface‐enhanced Raman scattering: Moving beyond the electromagnetic enhancement theory

Heeg

Mueller

Waßerroth

et al. 2020

J Raman Spectroscopy

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“…hot spots 1-10 nm) 16 , the methods are strictly separated into near and far-eld optical methods. Near-eld optical tip-based methods like s-SNOM-SERS 17 and functionalised TERS 18,19 or electron microscopy-based methods like PEEM 19 and STEM/EELS 20 as well as super resolution-imaging 16,21 enable nanoscale mapping of localised surface plasmon resonances (LSPRs) 20 , the electromagnetic eld enhancement [17][18][19] or of individual Raman bands 16,17,21 in hot spots and are important tools in fundamental research to study structural-functional relationships. Due to the high equipment expense, di cult handling and a low versatility these methods are however not common in applied analytical SERS research.…”

Section: Introductionmentioning

confidence: 99%

SERS background imaging – A versatile tool towards more reliable SERS analytics

Ebersbach

Münchberg

Freier

2020

Preprint

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Surface-enhanced Raman scattering (SERS) is a highly selective and sensitive straightforward analytical method, which is however not yet established in routine analysis due to a lack of reliability and reproducibility. To address this limitation, we show the distinct correlation of the ever-present but often neglected broad SERS background continuum with the SERS signal intensity of the analyte and how to exploit this correlation for an easy-to-handle, automatable and more reliable SERS measurement. First, fast and high-contrast imaging of the SERS substrate is performed for hot spot localisation utilizing the SERS background. Subsequently, highly enhanced SERS spectra are recorded at the centre of these spots. Furthermore, we correlate our SERS background imaging with other optical imaging modalities and electron microscopy to assess structure-property relationships. Monte Carlo simulations based on actual measurements illustrate the sampling error of a conventional SERS experiment and the advantages our method provides.

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“…Further signal enhancement is achieved when the analyte is placed on a metallic substrate, thus forming a nanoscale metallic junction. This mode is referred to as gap-mode TERS and has been used to probe a variety of molecular systems, such as small molecules, 8−12 nanostructured materials, and biomaterials. 13−21 Ideal metallic substrates for gap-mode TERS in the backscattering configuration are both atomically flat, reducing parasitic scattering processes, and thin enough to be optically transparent.…”

Section: Introductionmentioning

confidence: 99%

Plasmon-Mediated Drilling in Thin Metallic Nanostructures

2018

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Thin and ultraflat conductive surfaces are of particular interest to use as substrates for tip-enhanced spectroscopy applications. Tip-enhanced spectroscopy exploits the excitation of a localized surface plasmon resonance mode at the apex of a metallized atomic force microscope tip, confining and enhancing the local electromagnetic field by several orders of magnitude. This allows for nanoscale mapping of the surface with high spatial resolution and surface sensitivity, as demonstrated when coupled to local Raman measurements. In gap-mode tip-enhanced spectroscopy, the specimen of interest is deposited onto a flat metallic surface and probed by a metallic tip, allowing for further electromagnetic confinement and subsequent enhancement. We investigate here a geometry where a gold tip is used in conjunction with a silver nanoplate, thus forming a heterometallic platform for local enhancement. When irradiated, a plasmon-mediated reaction is triggered at the tip–substrate junction due to the enhanced electric field and the transfer of hot electrons from the tip to the nanoplate. This resulting nanoscale reaction appears to be sufficient to ablate the thin silver plates even under weak laser intensity. Such an approach may be further exploited for patterning metallic nanostructures or photoinduced chemical reactions at metal surfaces.

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High resolution scanning near field mapping of enhancement on SERS substrates: comparison with photoemission electron microscopy

Cited by 20 publications

References 52 publications

Experimental tests of surface‐enhanced Raman scattering: Moving beyond the electromagnetic enhancement theory

Experimental tests of surface‐enhanced Raman scattering: Moving beyond the electromagnetic enhancement theory

SERS background imaging – A versatile tool towards more reliable SERS analytics

Plasmon-Mediated Drilling in Thin Metallic Nanostructures

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