Feng Huimin, Dong Jianjie, Wu Xianxin, Yang Fengyou, Ma Lijun, Liu Xinfeng, Liu Qian
Opt Lett. 2020 Apr 1;45(7):2099-2102. doi: 10.1364/OL.389241.
The local field enhancement in plasmonic nanostructures is vital for surface enhanced Raman scattering (SERS). However, it remains a challenge to achieve a large local field enhancement at an illumination wavelength in the green waveband. Here we report on an ultra-large local field enhancement effect of isolated thick triangular silver nanoplates (ITTSNPs) on a silicon substrate at an illumination wavelength in the green waveband. We show that when the thickness of the ITTSNP is larger than a critical thickness depending on the illumination wavelength, a large local field enhancement with an enhancement factor (EF) greater than 350 can be achieved at an illumination wavelength in the green waveband, which is due to the excitation of strong localized surface plasmon polaritons only at three top apexes of the ITTSNP. Furthermore, we experimentally demonstrate that at an excitation wavelength of 514.5 nm, the average SERS EF of the ITTSNPs can exceed ${{10}^{11}}$10, and the sensitivity for the detection of Rhodamine 6 G molecules can reach ${{10}^{ - 12}};{\rm M}$10M.
等离子体纳米结构中的局域场增强对于表面增强拉曼散射（SERS）至关重要。然而，在绿色波段的照明波长下实现大的局域场增强仍然是一个挑战。在此，我们报道了在绿色波段照明波长下，硅衬底上孤立的厚三角形银纳米板（ITTSNP）的超大局域场增强效应。我们表明，当ITTSNP的厚度大于取决于照明波长的临界厚度时，在绿色波段照明波长下可实现增强因子（EF）大于350的大的局域场增强，这是由于仅在ITTSNP的三个顶角处激发了强局域表面等离激元极化激元。此外，我们通过实验证明，在514.5 nm的激发波长下，ITTSNP的平均SERS EF可超过10的11次方，并且检测罗丹明6G分子的灵敏度可达到10的-12次方摩尔。
