Au纳米粒子二聚体-Au片耦合体系“热点”的尺寸效应  

Size Effect on“Hot Spot”of Au Nanoparticle Dimer-Au Plate Coupling System

作　　者：曾自强 张晨杰[1] 徐敏敏[1] 姚建林[1] ZENG Ziqiang;ZHANG Chenjie;XU Minmin;YAO Jianlin(College of Chemistry,Chemical Engineering and Materials Science,Soochow University,Suzhou 215123,China)

机构地区：[1]苏州大学材料与化学化工学部,苏州215123

出　　处：《高等学校化学学报》2024年第6期130-137,共8页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:22172109,211773166)资助。

摘　　要：表面增强光谱“热点”效应一直是相关领域广受关注的主题,其中与尺寸和激发波长相关的动态“热点”转移效应的可控性是研究的重点和难点.本文利用有限元法(FEM)对Au纳米粒子球二聚体-Au片耦合体系进行了模拟计算,研究了激发波长和纳米粒子尺寸对体系不同间隙处电磁场增强的影响.结果表明,该体系所拥有的两种等离激元共振模式的分离和位置与纳米尺寸密切相关,并且影响该耦合体系的“热点”分布.当纳米粒子尺寸为30 nm,激发波长范围为450~535 nm和670~950 nm时,两种等离激元共振模式以协同效应为主,“热点”主要存在于粒子与粒子间隙;随着纳米粒子球尺寸增加至85~105 nm,激发波长范围分别为670~695nm和725~755 nm时,两种等离激元共振模式之间开始出现竞争效应,发现“热点”由粒子与粒子间隙处转移至粒子与金片间隙处.该研究结果为“热点”转移调控提供了新思路.The"hot spot"effect has attracted considerable attention in surface enhanced spectroscopy and relevant fields,especially for the controllable fabrication of the dynamic"hot spot"by using the size and excitation wavelength dependent transfer effect.Herein,the coupling system of spherical dimer of gold nanoparticles and gold plate is theoretically simulated by finite element method(FEM),and the effects of excitation wavelengths and nanoparticle sizes on the electromagnetic field enhancement at different gaps of the system are systematically investigated.The results demonstrated that the two modes of surface plasmon resonance were observed.As the size of nanoparticle is 30 nm and the excitation wavelength is 450—535 nm and 670—950 nm,the two plasmon resonance modes were mainly dominated by a cooperative effect,and“hot spot”mainly located in the particle-particle gap.As the size of nanoparticles was increased to 85 nm or even 105 nm,a competition effect between the two plasmon resonance modes was occurred for the excitation wavelengths of 670—695 nm and 725—755 nm.It resulted in the transformation of“hot spot”from particle-particle gap to particles-gold plate gap successfully.It was anticipated that the theoretical simulation provided an alternative approach for control and transfer on the“hot spot”and it was beneficial to design and fabricate the substrate with high performance of surface enhanced optical effect.

关 键 词：“热点” 表面等离极化激元 金纳米粒子二聚体 竞争效应 转移效应 

分 类 号：O647[理学—物理化学]