Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces, and The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Nanoscale. 2018 Mar 1;10(9):4398-4405. doi: 10.1039/c7nr08186c.
Tip-enhanced Raman spectroscopy (TERS), known as nanospectroscopy, has received increasing interest as it can provide nanometer spatial resolution and chemical fingerprint information of samples simultaneously. Since Ag tips are well accepted to show a higher TERS enhancement than that of gold tips, there is an urgent quest for Ag TERS tips with a high enhancement, long lifetime, and high reproducibility, especially for atomic force microscopy (AFM)-based TERS. Herein, we developed an electrodeposition method to fabricate Ag-coated AFM TERS tips in a highly controllable and reproducible way. We investigated the influence of the electrodeposition potential and time on the morphology and radius of the tip. The radii of Ag-coated AFM tips can be rationally controlled at a few to hundreds nanometers, which allows us to systematically study the dependence of the TERS enhancement on the tip radius. The Ag-coated AFM tips show the highest TERS enhancement under 632.8 nm laser excitation and a broad localized surface plasmon resonance (LSPR) response when coupled to a Au substrate. The tips exhibit a lifetime of 13 days, which is particularly important for applications that need a long measuring time.
尖端增强拉曼光谱（TERS），又称纳米光谱学，由于能够同时提供纳米级空间分辨率和样品的化学指纹信息，因此受到越来越多的关注。由于 Ag 尖端被广泛认为比金尖端具有更高的 TERS 增强效果，因此迫切需要具有高增强、长寿命和高重现性的 Ag TERS 尖端，特别是对于基于原子力显微镜（AFM）的 TERS。在此，我们开发了一种电沉积方法，以高度可控和可重复的方式制造 Ag 涂层 AFM TERS 尖端。我们研究了电沉积电位和时间对尖端形态和半径的影响。Ag 涂层 AFM 尖端的半径可以在几到几百纳米的范围内合理控制，这使我们能够系统地研究TERS 增强与尖端半径的关系。在耦合到 Au 基底时，Ag 涂层 AFM 尖端在 632.8nm 激光激发下表现出最高的 TERS 增强效果和宽的局域表面等离子体共振（LSPR）响应。尖端的寿命为 13 天，这对于需要长时间测量的应用尤为重要。
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