Advanced progress on tip-enhanced Raman spectroscopy and its applications

Abstract The diffraction limit of light fundamentally limits the spatial resolution of conventional optical microscopy. However, tip-enhanced Raman spectroscopy (TERS) which combines scanning probe microscopy with Raman spectroscopy overcomes this limitation by utilizing near-field technique with a plasmonic tip. This enables the simultaneous acquisition of morphology and optical response of materials present on the surface. As a result, the nanoscale features of surfaces and their optical signals, which are not accessible through far-field signals, can be measured at sub-nanometer resolution. In this review, we first provide a brief introduction followed by an overview of the essential components of TERS, including the working principle of TERS and fabrication methods of plasmonic tips. Subsequently, we will look into the advances in the instrumentation of TERS, such as the operation of TERS in various environments, dynamic control using a tip, and the implementation of adaptive optics in TERS. Finally, we will review very recent TERS studies in selected research areas, including biomaterials, 2D materials, catalytic processes, and single-molecule chemistry.