Wei Yong, Pei Huan, Yan Baoxin, Zhu Yanying
College of Information Science and Engineering, Yanshan University, Qinhuangdao, 066004, People's Republic of China.
Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, People's Republic of China.
J Phys Condens Matter. 2021 Nov 4;34(4). doi: 10.1088/1361-648X/ac316d.
The theoretical research on surface enhanced Raman spectroscopy (SERS) of triangular plate dimer (TPD) is of great significance for the design of experimental substrates. In this paper, the SERS properties of the TPD with Au, Ag, Al and Cu have been theoretical investigated in the ultra-ultraviolet, visible and near-infrared region. The influence of the TPD configuration, including the tip radian, the dimer distance and the aspect ratio on the electric field, Raman enhancement and spatial resolution are studied by the finite element method. The results show that there are dipole resonance band and quadruple dipole resonance band in the surface plasmon resonance band of TPD. The tip radian and dimer distance play the dominant role in the electric field enhancement, and the aspect ratio can be mainly used to tune the peak position of the electric field. The smaller tip radian and dimer distance will produce a stronger localized electric field and a small red shift of the peak position. Adjusting the aspect ratio can tune the position of electric field peak from ultraviolet (UV) to near-infrared without changing the peak value of the electric field significantly, especially for Al TPD. The maximum Raman enhancement factor of Au, Ag and Cu all reach 11 orders of magnitude, and 9 orders of magnitude for Al. The spatial resolution changes linearly with the gap distance, and the maximum spatial distributions of Au, Ag, Al and Cu achieve 0.65 nm, 0.67 nm, 0.69 nm and 0.70 nm with the dimer distance of 1 nm. Our results not only provide a better theoretical guidance for the optimization of TPD substrates in the SERS experiment, but also extend its application scope from ultra-UV to near-infrared range.
三角形平板二聚体（TPD）表面增强拉曼光谱（SERS）的理论研究对实验基底的设计具有重要意义。本文对含Au、Ag、Al和Cu的TPD在极紫外、可见光和近红外区域的SERS特性进行了理论研究。采用有限元方法研究了TPD结构，包括尖端弧度、二聚体间距和长宽比，对电场、拉曼增强和空间分辨率的影响。结果表明，TPD的表面等离子体共振带中存在偶极共振带和四极偶极共振带。尖端弧度和二聚体间距在电场增强中起主导作用，长宽比主要用于调节电场的峰值位置。较小的尖端弧度和二聚体间距会产生更强的局域电场和较小的峰值位置红移。调节长宽比可将电场峰值位置从紫外（UV）调至近红外，且不会显著改变电场峰值，特别是对于Al TPD。Au、Ag和Cu的最大拉曼增强因子均达到11个数量级，Al为9个数量级。空间分辨率随间隙距离线性变化，当二聚体间距为1 nm时，Au、Ag、Al和Cu的最大空间分布分别达到0.65 nm、0.67 nm、0.69 nm和0.70 nm。我们的结果不仅为SERS实验中TPD基底的优化提供了更好的理论指导，还将其应用范围从极紫外扩展到了近红外区域。
