Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering
Visualizing Electric Fields at Au(111) Step Edges via Tip-Enhanced Raman Scattering
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DOI：
10.1021/acs.nanolett.7b04027
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发表时间：
2017-11-01
期刊：
影响因子：
10.8
通讯作者：
El-Khoury, Patrick Z.
中科院分区：
文献类型：
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作者：
Bhattarai, Ashish;Joly, Alan G.;El-Khoury, Patrick Z.
尖端增强拉曼散射(TERS)可以用来在纳米尺度上成像等离子体增强的局部电场。这是通过使用涂有4-巯基苯甲腈分子的银色原子力显微镜尖端记录的环境测量来说明的，并用于对Au(111)表面的台阶边缘进行成像。观察到的二维TERS图像唯一地映射了671 nm激发后Au(111)台阶边缘的电场。我们证明我们的测量不仅对增强电场的空间变化很敏感，而且对它们的矢量分量也很敏感。我们还从实验上证明：(I)在使用额定半径为100-200 nm的波纹针尖的TERS纳米显微镜中，可以获得很小的纳米精度，并且(Ii)TERS信号不一定表现出预期的E(4)依赖关系。总而言之，我们通过TERS阐述了电场成像的概念，并建立了我们的观测与传统TERS化学成像测量之间的联系。
Tip-enhanced Raman scattering (TERS) can be used to image plasmon-enhanced local electric fields on the nanoscale. This is illustrated through ambient TERS measurements recorded using silver atomic force microscope tips coated with 4-mercaptobenzonitrile molecules and used to image step edges on an Au(111) surface. The observed two-dimensional TERS images uniquely map electric fields localized at Au(111) step edges following 671 nm excitation. We establish that our measurements are not only sensitive to spatial variations in the enhanced electric fields hut also to their vector components. We also experimentally demonstrate that (i) few nanometer precision is attainable in TERS nanoscopy using corrugated tips with nominal radii on the order of 100-200 nm, and (ii) TERS signal's do not necessarily exhibit the expected E(4 )dependence. Overall, we illustrate the concept of electric field imaging via TERS and establish the connections between our observations and conventional TERS chemical imaging measurements.