Excitation of the Tunable Longitudinal Higher-Order Multipole SPR Modes by Strong Coupling in Large-Area Metal Sub-10 nm-Gap Array Structures and Its Application

• Published in: Journal of physical chemistry. C Vol. 120; no. 43; pp. 24932 - 24940
• Main Authors: Qi, Jiwei, Xiang, Yinxiao, Yan, Weiguo, Li, Meng, Yang, Liusiyang, Chen, Zongqiang, Cai, Wei, Chen, Jing, Li, Yudong, Wu, Qiang, Yu, Xuanyi, Sun, Qian, Xu, Jingjun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 03.11.2016
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b05108

The excitation of the higher-order multipole localized surface plasmon resonance (LSPR) modes in sub-10 nm-gap plasmonic structure is desired in many plasmon enhancement applications. However, unfortunately, the higher-order multipole modes are either hard to be excited by light or make a very small contribution to electromagnetic enhancement, generally. In this paper, we demonstrate that tunable longitudinal higher-order multipole LSPR modes can be excited in large-area metal sub-10 nm-gap structures based on mature PS@Au core-halfshell ordered array plasmonic nanostructure by experiment and numerical simulation. Our results show that the longitudinal higher-order multipole SPR modes can be regarded as the like-cavity modes and can be excited effectively in strong coupling sub-10 nm-gap array structures and, furthermore, make a major contribution to the huge electromagnetic enhancement. Additionally, the longitudinal higher-order multipole SPR modes can be tuned easily by changing the longitudinal size of the plasmonic structure. As a benefit from this, we fabricated the optimized ultrasensitive surface-enhanced Raman scattering (SERS) substrate successfully. Our study provides a new view for design of surface plasmon resonance enhanced devices.