Wang Rui, He Zhe, Sokolov Alexei V, Kurouski Dmitry
J Phys Chem Lett. 2020 May 21;11(10):3815-3820. doi: 10.1021/acs.jpclett.0c01021. Epub 2020 May 1.
Gold nanoplates (AuNPLs) enable the gap-mode configuration of tip-enhanced Raman spectroscopy (TERS). This allows for low-concentration molecular sensing and high-resolution imaging. Compared with non-gap-mode TERS, the gap plasmon provides significantly higher enhancement factors. In addition, AuNPLs exhibit a lightning rod or edge effect, further enhancing the laser field and increasing the spectroscopic sensitivity. In this study, we investigate the relationship between the thickness of AuNPLs and the intensity of the spontaneous Raman signal produced by 4-nitrobenzenethiol, a reporter molecule used in TERS. Our experimental and theoretical results show that the intensity of TERS spectra increases with an increase in the thickness of the AuNPLs. This study of the thickness dependence of AuNPL allows us to find a configuration with maximal nanoplasmonic effects. Moreover, the electromagnetic interaction of the AuNPL with the tip, positioned near the AuNPL's edge, results in a plasmonic nanoantenna configuration for field enhancement, with important promise for future applications to nanobioimaging and biosensing.
金纳米片（AuNPLs）实现了针尖增强拉曼光谱（TERS）的间隙模式配置。这使得低浓度分子传感和高分辨率成像成为可能。与非间隙模式TERS相比，间隙等离子体激元提供了显著更高的增强因子。此外，AuNPLs表现出避雷针或边缘效应，进一步增强了激光场并提高了光谱灵敏度。在本研究中，我们研究了AuNPLs的厚度与4-硝基苯硫酚（一种用于TERS的报告分子）产生的自发拉曼信号强度之间的关系。我们的实验和理论结果表明，TERS光谱的强度随着AuNPLs厚度的增加而增加。对AuNPL厚度依赖性的这项研究使我们能够找到具有最大纳米等离子体效应的配置。此外，AuNPL与位于AuNPL边缘附近的针尖之间的电磁相互作用导致了用于场增强的等离子体纳米天线配置，对未来在纳米生物成像和生物传感中的应用具有重要前景。
