Yue Weisheng, Kravets Vasyl, Pu Mingbo, Wang Changtao, Zhao Zeyu, Hu Zhirun
State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering, Institute of Optics and Electronics, Chinese Academy of Sciences, PO Box 350, Chengdu 610209, People's Republic of China.
Nanotechnology. 2019 Nov 15;30(46):465206. doi: 10.1088/1361-6528/ab3b69.
Due to the ability to tightly confine electromagnetic energy, plasmonic nanoantennas have been widely studied for surface-enhanced infrared absorption (SEIRA) spectroscopy, surface-enhanced Raman spectroscopy as well as refractive index sensing. However, most of the nanoantennas are limited by narrow resonant band and it is rather challenging to detect multiple molecular fingerprints. In this work, we report dual and triple- resonant pad-rod plasmonic nanoantennas which are nanorods with large pads at their ends placed above gold (Au) mirror separated by a spacer layer. By adjusting the geometries, the nanoantennas have demonstrated dual and triple resonant bands enabling detection of molecular fingerprints at different wavelength. The calculated maximum SEIRA enhancement factor is around 1.8 × 10, which is among the highest reported so far. The pad-rod plasmonic nanoantennas have been used for the detection of molecules of polymethyl methacrylate (PMMA) by SEIRA and fingerprints of C=O and C-H bands are clearly identified. This work has shown that the multiple-resonant pad-rod plasmonic nanoantennas are promising for chemical and biomolecular sensing by the detection of vibrational fingerprints with SEIRA.
由于能够紧密限制电磁能量，等离子体纳米天线已被广泛研究用于表面增强红外吸收（SEIRA）光谱、表面增强拉曼光谱以及折射率传感。然而，大多数纳米天线受到窄共振带的限制，检测多个分子指纹具有相当大的挑战性。在这项工作中，我们报道了双共振和三共振垫棒等离子体纳米天线，它们是末端带有大垫的纳米棒，放置在由间隔层隔开的金（Au）镜上方。通过调整几何结构，这些纳米天线展示出双共振和三共振带，能够在不同波长下检测分子指纹。计算得到的最大SEIRA增强因子约为1.8×10，这是迄今为止报道的最高值之一。垫棒等离子体纳米天线已通过SEIRA用于检测聚甲基丙烯酸甲酯（PMMA）分子，并且清晰地识别出了C=O和C-H带的指纹。这项工作表明，多共振垫棒等离子体纳米天线通过利用SEIRA检测振动指纹，在化学和生物分子传感方面具有广阔前景。
