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Nanoscale chemical imaging of solid-liquid interfaces using tip-enhanced Raman spectroscopy

Kumar, N; Su, W T; Vesely, M; Weckhuysen, B M; Pollard, A J; Wain, A J (2018) Nanoscale chemical imaging of solid-liquid interfaces using tip-enhanced Raman spectroscopy. Nanoscale, 10 (4). pp. 1815-1824.

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Abstract

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for non-destructive and label-free surface molecular mapping at the nanoscale. However, to date nanoscale resolution chemical imaging in a liquid environment has not been possible, in part due to the lack of robust TERS probes that are stable when immersed in a liquid. In this work, we have addressed this challenge by developing plasmonically-active TERS probes with a multilayer metal coating structure that can be successfully used within a liquid environment. Using these novel TERS probes, we have compared the plasmonic enhancement of TERS signals in air and water environments for both gap mode and non-gap mode configurations and show that in both cases the plasmonic enhancement decreases in water. To better understand the signal attenuation in water, we have performed numerical simulations that revealed a negative correlation between the electric field enhancement at the TERS probe-apex and the refractive index of the surrounding medium. Finally, using these robust probes we demonstrate TERS imaging with nanoscale spatial resolution in a water environment for the first time by employing single-wall carbon nanotubes as a model sample. Our findings are expected to broaden the scope of TERS to a range of scientific disciplines in which nanostructured solid-liquid interfaces play a key role.

Item Type: Article
Keywords: Tip-ehanced Raman spectroscopy, Nanoscale chemical mapping in liquid, plasmonic signal enhancement, single-wall carbon nanotubes
Subjects: Analytical Science > Trace Analysis and Electrochemistry
Divisions: Engineering, Materials & Electrical Science
Identification number/DOI: 10.1039/c7nr08257f
Last Modified: 20 Apr 2018 12:47
URI: http://eprintspublications.npl.co.uk/id/eprint/7873

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