电子能量损失谱探测银纳米棒与介质层强耦合的数值模拟  

Numerical simulation of strong coupling between silver nanorod and dielectric layer detected by electron energy loss spectrum

作　　者：赵世杭 张元[2] 吕思远 程少博[2] 郑长林 王鹿霞 Zhao Shi-Hang;Zhang Yuan;Lü Si-Yuan;Cheng Shao-Bo;Zheng Chang-Lin;Wang Lu-Xia(Institute of Theoretical Physics,Department of Physics,School of Mathematics and Physics,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Material Physics Ministry of Education,School of Physics,Zhengzhou University,Zhengzhou 450052,China;State Key Laboratory of Surface Physics,Department of Physics,Fudan University,Shanghai 200438,China)

机构地区：[1]北京科技大学数理学院物理系,理论物理研究所,北京100083 [2]郑州大学物理学院,材料物理教育部重点实验室,郑州450052 [3]复旦大学物理学系,应用表面物理国家重点实验室,上海200438

出　　处：《物理学报》2022年第14期269-279,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21961132023,12004344,11774026,61871134)资助的课题.

摘　　要：表面等离激元与量子发射体间的强耦合现象通常通过散射、吸收以及荧光等远场光谱探测方法进行研究.利用高度聚焦的电子束,电子能量损失谱能够实现亚纳米尺度的局域探测,可以更加有效地研究强耦合现象.本文在理论上分别模拟了银纳米棒、介质材料以及介质层包裹银纳米棒复合结构的电子能量损失谱.得到了可以与实验结果比拟的银纳米棒表面等离激元的电子能量损失谱.在上述复合结构的电子能量损失谱中观察到了谱峰的拉比劈裂,探究了银纳米棒尺寸对拉比劈裂的影响.分别在红外、可见光波段讨论了介质层的元激发与银纳米棒偶极辐射及高阶非辐射表面等离激元模式间的强耦合现象,从损失谱的空间分布成像角度探讨了强耦合引起的杂化等离激子(plexciton)的形成.本研究对强耦合现象的进一步实验和理论研究具有指导意义.The strong coupling phenomenon between surface plasmons and quantum emitters has received extensive attention in recent years. It is usually studied by the far-field spectral detection method such as scattering,absorption, and fluorescence. In the electron energy loss spectroscopy(EELS), highly focused electron beams are used for implementing the local detection on a sub-nanometer scale, which can be more effective to study strong coupling. In this work, the electron energy loss spectrum of silver nanorods, dielectric materials and their composite core-shell nanostructures are theoretically simulated respectively, and the energy and mode characteristics of surface plasmons on the silver nanorods and the excitation characteristics of dielectric materials are obtained. The electron energy loss spectrum of surface plasmon is basically consistent with the related experimental result. Rabi splitting of spectral peaks is observed in the electron energy loss spectra of the above composite structures, and the effect of Ag nanorod size on Rabi splitting is explored. The strong coupling between the radiative dipolar and non-radiative higher-order plasmon with the excitation of the dielectric materials in the infrared and visible band is discussed, and the corresponding dispersion relation is analyzed with the coupled oscillator mode. Furthermore, the plexciton caused by strong coupling are discussed from the perspective of spatial distribution of loss spectrum imaging. Our study builds the basis for further theoretical study, and can guide the further experimental research.

关 键 词：电子能量损失谱 表面等离激元 强耦合 

分 类 号：TB383.1[一般工业技术—材料科学与工程]