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Tip-enhanced Raman Spectroscopy (TERS) is a nanoscale chemical analysis and imaging method with a spatial resolution on the order of 10 nm. TERS is similar to SERS, and relies on enhancement of the local electromagnetic field in the vicinity of a plasmonic nanostructure that is scanned over a sample by means of a scanning probe microscope, using either AFM or STM feedback. The local enhancement of Raman scattered light is many orders of magnitude, large enough to render monomolecular films spectroscopically visible that would otherwise be optically too thin to be analyzed with conventional vibrational spectroscopy.
The working principle and experimental realization of TERS will first be presented [1]. An important advance concerns the production long-lived silver TERS tips that, thanks to the presence of a chemical protection layer, live for many weeks as opposed to the typical lifetime of ≈1 day for bare Ag tips [2]. The focus of this presentation will be on applications of TERS to the spatially resolved chemical analysis of molecular nanomaterials, including graphene, self-assembled monolayers [3], and a novel class of materials, 2D polymers [4].
References:
[1] J. Stadler, T. Schmid, and R. Zenobi, Developments in and Practical Guidelines for Tip-Enhanced Raman Spectroscopy, Nanoscale 4, 1856 – 1870 (2012).
[2] L. Opilik, Ü. Dogan, C.-Y. Li, B. Stephanidis, J.-F. Li, an R. Zenobi, Chemical Production of Thin Protective Coatings on Optical Nanotips for Tip-Enhanced Raman Spectroscopy, J. Phys. Chem. C 120, 20828-20832 (2016).
[3] W.-I. Lin et al., Tip-Enhanced Raman Spectroscopic Imaging Shows Segregation within Binary Self-Assembled Thiol Monolayers at Ambient Conditions, Anal. Bioanal. Chem. 407, 8197-8204 (2015).
[4] W. Dai et al., Synthesis of a Two-Dimensional Covalent Organic Monolayer through Dynamic Imine Chemistry at the Air/Water Interface, Angew. Chem. Int. Ed. 55, 213-217 (2016).
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