Interdisciplinary School of Green Energy, Low Dimensional Carbon Materials Center, UNIST, Korea.
Nanoscale. 2013 Mar 7;5(5):1836-42. doi: 10.1039/c3nr33498h. Epub 2013 Feb 5.
Dual-scale diamond-shaped gold nanostructures (d-DGNs) with larger scale diamond-shaped gold nanoposts (DGNs) coupled to smaller scale gold nanoparticles have been fabricated via interference lithography as a highly reliable and efficient substrate for surface enhanced Raman scattering (SERS). The inter- and intra-particle plasmonic fields of d-DGNs are varied by changing the periodicity of the DGNs and the density of gold nanoparticles. Because of the two different length scales in the nanostructures, d-DGNs show multipole plasmonic peaks as well as dipolar plasmonic peaks, leading to a SERS enhancement factor of greater than 10(9). Simulations are carried out by finite-difference time-domain (FDTD) methods to evaluate the dependence of the inter- and intra-particle plasmonic field and the results are in good agreement with the experimentally obtained data. Our studies reveal that the combination of two different length scales is a straightforward approach for achieving reproducible and great SERS enhancement by light trapping in the diamond-shaped larger scale structures as well as efficient collective plasmon oscillation in the small size particles.
双尺度菱形金纳米结构（d-DGNs）由较大尺度的菱形金纳米柱（DGNs）与较小尺度的金纳米粒子结合而成，通过干涉光刻技术制备，是一种高可靠性和高效率的表面增强拉曼散射（SERS）基底。通过改变 DGNs 的周期性和金纳米粒子的密度，可以改变 d-DGNs 的粒子间和粒子内等离子体场。由于纳米结构中有两个不同的长度尺度，d-DGNs 显示出多极等离子体峰和偶极等离子体峰，导致 SERS 增强因子大于 10^9。通过有限差分时域（FDTD）方法进行模拟，以评估粒子间和粒子内等离子体场的依赖性，结果与实验获得的数据非常吻合。我们的研究表明，通过在较大尺度的菱形结构中光捕获以及在小尺寸粒子中有效集体等离子体振荡来实现可重复的、较大的 SERS 增强，两个不同长度尺度的结合是一种简单直接的方法。
