Nanoscale Raman Imaging with Nanogold-Topped AFM Probes Fabricated by Area-Selective Electroless Deposition
Nanoscale Raman Imaging with Nanogold-Topped AFM Probes Fabricated by Area-Selective Electroless Deposition
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DOI：
10.1149/2.0561814jes
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发表时间：
2018
影响因子：
3.9
通讯作者：
Hiroki Itasaka;M. Nishi;M. Shimizu;Yoshito Okuno;S. Kashiwagi;N. Naka;K. Hirao
中科院分区：
文献类型：
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作者：
Hiroki Itasaka;M. Nishi;M. Shimizu;Yoshito Okuno;S. Kashiwagi;N. Naka;K. Hirao
一个单一的金纳米结构被成功地沉积在原子力显微镜（AFM）的硅探针的尖端顶点在无电和区域选择性的方式。用聚焦离子束（FIB）照射市售硅原子力显微镜探针的尖端以去除原生氧化层，然后将探针暴露于含有氯化钠（NaCl）的氯金酸（HAuCl 4）水溶液。一个单一的金纳米结构选择性地生长在FIB照射的顶点作为电子转移的结果，从硅到溶液通过FIB照射的硅表面。这种电子转移是由电子的电化学电位差驱动的。在纯HAuCl4水溶液中加入NaCl，提高了金生长的面积选择性，减小了金的尺寸，从而获得了理想的金作为针尖增强拉曼光谱（TERS）针尖的几何形状，提高了空间分辨率，增强了电场强度.我们的探针提供了碳纳米管的TERS成像的空间分辨率为10 nm，和增强因子高达2.2× 105的偶氮苯硫醇自组装单分子层的间隙模式配置与侧照明光学设置。
A single gold nanostructure is successfully deposited at the tip apex of a silicon probe for atomic force microscopes (AFM) in an electroless and area-selective manner. The tip apex of a commercially available silicon AFM probe is irradiated with a focused ion beam (FIB) to remove the native oxide layer, and then the probe was exposed to chloroauric acid (HAuCl 4) aqueous solution containing sodium chloride (NaCl). A single gold nanostructure selectively grows at the FIB-irradiated apex as a consequence of electron transfer from silicon to the solution through the FIB-irradiated silicon surface. This electron transfer is driven by the difference in the electrochemical potential of electrons. NaCl, added to a pure HAuCl 4 aqueous solution, improves the area-selectivity of gold growth and decreases the size of gold, resulting in desired geometry of gold as the tip apex for tip-enhanced Raman spectroscopy (TERS) in terms of the spatial resolution and the enhancement of the electric field. Our probes provide TERS imaging of a carbon nanotube with a spatial resolution of 10 nm, and enhancement factors up to 2.2× 10 5 for an azobenzene thiol self-assembled monolayer in the gap-mode configuration with a side-illumination optical setup.