Le TERS, ou comment obtenir une signature chimique à l’échelle nanométrique

Abstract

Le TERS pour tip enhanced raman scattering, est une technique de pointe (dans tous les sens du terme) basée sur l’amplification du signal Raman relative à la résonance de plasmons de surface. Cette technique non-destructive, qui ne nécessite pas de marquage particulier, permet de caractériser un échantillon à l’échelle nanométrique. Le TERS s’impose aujourd’hui pour sonder les propriétés physico-chimiques des nanomatériaux et participer ainsi au développement de nouvelles applications dans le domaine des nanotechnologies.

Challenges and Opportunities of Tip-Enhanced Raman Spectroscopy in Liquids

“…In the recent years, TERS in liquid has revealed nanoscale chemical images of molecules containing a benzene ring, including thiophenol, ,,,, CNT, , and others. , Furthermore, EC-TERS measurements have expanded our knowledge of the redox compounds such as NB ,,,, and PANI . Moreover, this method has also enabled new insights into various chemical transformations, including the conversion of p -ATP to DMAB; ,, potential-dependent changes of 4-PBT, ,,, adenine, 2-AQ, ,, and several other chemical reactions; ,,, monitoring of the single amyloid-aggregates of the Aβ 1–42 decarboxylation of p -MBA; and pH sensing with p -MBA- and p -ATP-modified tips .…”

“…The distortion can be avoided or reduced by various approaches for the side illumination and collection setup. Some groups used a water- or oil-immersion objective ,,, or an additional lens in front of the side objective or tilted the sample to achieve a better light direction , to minimize the distortion problems of the optical path way. An optical method, such as the SLM, was used to manipulate the far field focus through settings.…”

“…In addition, the laser spots can form reflections in the liquid. To prevent this, the optical alignment plays an essential role . For EC-AFM measurements in liquid, it is important to find the right resonance for the tip.…”

“…The side illumination and collection setup enables measurements on transparent or opaque sample carriers and allows AFM, SFM, and STM feedback modes. The areas of application are in biology, AFM, , and predominantly EC-STM-TERS measurements in the field of molecular configuration , and the study of the electron transfer reaction, redox reactions, and catalytic behavior. , Tables and summarize the main results to date, categorized by feedback type (SFM, STM, and AFM). Table compares the technical details, while Table presents results obtained and chemical bonds measured in these works.…”

“…There was also a lens in the cantilever holder for the correction of the diode reflection in water. AFM topographic images and TERS in water were implemented with CNT and graphene oxide flakes at the same time with a chemical sensitivity down to the pixel size (1.7 nm) and a spatial resolution of 20 nm along a line across the CNT …”