Toward High-Contrast Atomic Force Microscopy-Tip-Enhanced Raman Spectroscopy Imaging: Nanoantenna-Mediated Remote-Excitation on Sharp-Tip Silver Nanowire Probes
Toward High-Contrast Atomic Force Microscopy-Tip-Enhanced Raman Spectroscopy Imaging: Nanoantenna-Mediated Remote-Excitation on Sharp-Tip Silver Nanowire Probes
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DOI：
10.1021/acs.nanolett.8b03399
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发表时间：
2019-01-01
期刊：
影响因子：
10.8
通讯作者：
Liu, Ming
中科院分区：
文献类型：
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作者：
Ma, Xuezhi;Zhu, Yangzhi;Liu, Ming
尖端增强拉曼光谱（TERS）成像技术被设计为通过利用由扫描探针的尖端顶点处的金属纳米结构支持的等离子体共振来提供具有纳米级空间分辨率的相关形态和化学信息。然而，受这些纳米结构的散射截面的限制，只有一小部分入射光可以耦合到等离子体共振以产生拉曼信号。然后，未耦合的光直接激发具有衍射极限分辨率的背景光谱，这成为经常模糊TERS图像的背景噪声。在这里，我们演示了如何解决这个问题，可以通过物理分离的光激发区域的拉曼信号产生区域上的扫描探头。远程激发TERS（RE-TERS）探针，它可以用一个简单的，鲁棒的和可重复的方法制造，利用银纳米粒子作为纳米天线介导的自由空间激发光的耦合到传播的表面等离子体激元（SPPs）在一个尖锐的尖端银纳米线远程激发拉曼信号。使用这种RE-TERS探针，在单壁碳纳米管样品上展示了10 nm的空间分辨率，并绘制了单层二硫化钼（MoS 2）中的应变分布。
The tip-enhanced Raman spectroscopy (TERS) imaging technique is designed to provide correlated morphological and chemical information with a nanoscale spatial resolution by utilizing the plasmonic resonance supported by metallic nanostructures at the tip apex of a scanning probe. However, limited by the scattering cross sections of these nanostructures, only a small fraction of the incident light can be coupled to the plasmonic resonance to generate Raman signals. The uncoupled light then directly excites background spectra with a diffraction-limited resolution, which becomes the background noise that often blurs the TERS image. Here, we demonstrate how this problem can be solved by physically separating the light excitation region from the Raman signal generation region on the scanning probe. The remote-excitation TERS (RE-TERS) probe, which can be fabricated with a facile, robust and reproducible method, utilizes silver nanoparticles as nanoantennas to mediate the coupling of free-space excitation light to propagating surface plasmon polaritons (SPPs) in a sharp-tip silver nanowire to excite Raman signals remotely. With this RE-TERS probe, a 10 nm spatial resolution was demonstrated on a single-walled carbon nanotube sample, and the strain distribution in a monolayer molybdenum disulfide (MoS2) was mapped.