Toroidal dipole-modulated dipole-dipole double-resonance in colloidal gold rod-cup nanocrystals for improved SERS and secondharmonic generation  

作　　者：Hao-Sen Kang Wen-Qin Zhao Tao Zhou Liang Ma Da-Jie Yang Xiang-Bai Chen Si-Jing Ding Qu-Quan Wang 

机构地区：[1]Hubei Key Laboratory of Optical Information and Pattern Recognition,Wuhan Institute of Technology,Wuhan 430205,China [2]School of Mathematics and Physics,China University of Geosciences(Wuhan),Wuhan 430074,China [3]Mathematics and Physics Department,North China Electric Power University,Beijing 102206,China [4]School of Science,Department of Physics,Southern University of Science and Technology,Shenzhen 518055,China

出　　处：《Nano Research》2022年第10期9461-9469,共9页纳米研究（英文版）

基　　金：funded by the National Natural Science Foundation of China(Nos.11904270 and 11904332);Hubei Key Laboratory of Optical Information and Pattern Recognition(Nos.202004 and 202010),Wuhan Institute of Technology.

摘　　要：Colloidal metal nanocrystals(NCs)show great potential in plasmon-enhanced spectroscopy owing to their attractive and structure-depended plasmonic properties.Herein,unique Au rod-cup NCs,where Au nanocups are embedded on the one or two ends of Au nanorods(NRs),are successfully prepared for the first time via a controllable wet-chemistry strategy.The Au rod-cup NCs possess multiple plasmon modes including transverse and longitudinal electric dipole(TED and LED),magnetic dipole(MD),and toroidal dipole(TD)modulated LED resonances,producing large extinction cross-section and huge near-field enhancements for plasmon-enhanced spectroscopy.Particularly,Au rod-cup NCs with two embedded cups show excellent surface-enhanced Raman spectroscopy(SERS)performance than Au NRs(75.6-fold enhancement excited at 633 nm)on detecting crystal violet owing to the strong electromagnetic hotspots synergistically induced by MD,LED,and TED-based plasmon coupling between Au cup and rod.Moreover,the strong TD-modulated dipole-dipole double-resonance and MD modes in Au rod-cup NCs bring a 37.3-fold enhancement of second-harmonic generation intensity compared with bare Au NRs,because they can efficiently harvest photoenergy at fundamental frequency and generate large near-field enhancements at second-harmonic wavelength.These findings provide a strategy for designing optical nanoantennas for plasmon-enhanced applications based on multiple plasmon modes.

关 键 词：PLASMON toroidal dipole near-field enhancement surface-enhanced Raman spectroscopy(SERS) second-harmonic generation 

分 类 号：TB383[一般工业技术—材料科学与工程]