title: Tip-enhanced Raman spectroscopy: tip-related issues.
abstract: After over 15 years of development, tip-enhanced Raman spectroscopy (TERS) is now facing a very important stage in its history. TERS offers high detection sensitivity down to single molecules and a high spatial resolution down to sub-nanometers, which make it an unprecedented nanoscale analytical technique offering molecular fingerprint information. The tip is the core element in TERS, as it is the only source through which to support the enhancement effect and provide the high spatial resolution. However, TERS suffers and will continue to suffer from the limited availability of TERS tips with a high enhancement, good stability, and high reproducibility. This review focuses on the tip-related issues in TERS. We first discuss the parameters that influence the enhancement and spatial resolution of TERS and the possibility to optimize the performance of a TERS system via an in-depth understanding of the enhancement mechanism. We then analyze the methods that have been developed for producing TERS tips, including vacuum-based deposition, electrochemical etching, electrodeposition, electroless deposition, and microfabrication, with discussion on the advantages and weaknesses of some important methods. We also tackle the issue of lifetime and protection protocols of TERS tips which are very important for the stability of a tip. Last, some fundamental problems and challenges are proposed, which should be addressed before this promising nanoscale characterization tool can exert its full potential. Graphical Abstract ᅟ.
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors: Teng-Xiang
authors: TX
authors: Huang
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors: Sheng-Chao
authors: SC
authors: Huang
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors: Mao-Hua
authors: MH
authors: Li
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors: Zhi-Cong
authors: ZC
authors: Zeng
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China. wangxiang@xmu.edu.cn.
authors: Xiang
authors: X
authors: Wang
authors: State Key Laboratory of Physical Chemistry of Solid Surface, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Key Laboratory of Analytical Sciences, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China. bren@xmu.edu.cn.
authors: Bin
authors: B
authors: Ren
mesh_terms: D000818:Animals; D004867:Equipment Design; D006801:Humans; D018625:Microscopy, Atomic Force / Q000295:instrumentation*; D055616:Microtechnology; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000295:instrumentation; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
keywords: Coating; Electrochemical etching; Protection; TERS; Tip