Huang Teng-Xiang, Huang Sheng-Chao, Li Mao-Hua, Zeng Zhi-Cong, Wang Xiang, Ren Bin
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.
Anal Bioanal Chem. 2015 Nov;407(27):8177-95. doi: 10.1007/s00216-015-8968-8. Epub 2015 Aug 28.
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.
经过15年多的发展，针尖增强拉曼光谱（TERS）如今正面临其发展历程中一个非常重要的阶段。TERS具有高达单分子水平的检测灵敏度以及低至亚纳米级的高空间分辨率，这使其成为一种能提供分子指纹信息的前所未有的纳米级分析技术。针尖是TERS的核心元件，因为它是支持增强效应并提供高空间分辨率的唯一来源。然而，TERS一直且仍将面临具有高增强效果、良好稳定性和高重现性的TERS针尖难以获得的问题。本综述聚焦于TERS中与针尖相关的问题。我们首先讨论影响TERS增强效果和空间分辨率的参数，以及通过深入理解增强机制来优化TERS系统性能的可能性。然后我们分析已开发出的用于制备TERS针尖的方法，包括基于真空的沉积法、电化学蚀刻法、电沉积法、化学镀法和微加工法，并讨论一些重要方法的优缺点。我们还探讨了TERS针尖的寿命和保护方案问题，这对针尖的稳定性非常重要。最后，提出了一些在这种有前景的纳米级表征工具充分发挥其潜力之前应解决的基本问题和挑战。图形摘要ᅟ
