光谱学与光谱分析, 2016, 36 (11): 3470, 网络出版: 2016-12-30  

Ag-Al纳米球二聚体的光学性质研究

Optical Properties of Ag-Al Nanosphere Heterodimer
作者单位
1 中国卫星海上测控部, 江苏 江阴 214431
2 西安交通大学理学院, 陕西 西安 710049
3 西安工程大学理学院, 陕西 西安 710048
摘要
金属纳米材料因其表面等离子体共振特性而备受关注。 异质结构的金属纳米材料的光学特性相比于同质结构因其材料的不同破坏了原有结构的对称性, 对称性的破坏将引起光学性质的改变, 相邻两个颗粒之间的相互作用会产生Fano共振。 Fano共振是由异质纳米结构的表面等离子体共振耦合引起的, 通过合理地调控表面等离子体共振的耦合, 将进一步调控Fano共振的强度同时促使异质结构的电场增强特性和辐射特性得到进一步优化。 受金银等贵金属的带间跃迁影响, 金属铝纳米材料成为研究紫外-近紫外光区的表面等离子体共振研究最佳选择。 采用有限时域差分方法研究了Ag-Al纳米球二聚体的光学特性。 研究了Ag和Al纳米球组成的二聚体的吸收光谱与入射光偏振方向、 纳米球半径、 颗粒间距和介质折射率等几何结构及物理参数的关系, 并深入讨论了二聚体的局域场分布规律; 讨论了获取更高效的Fano共振光谱的方法。 由于材料的对称性被破坏, 异质二聚体的光学性质与同质二聚体明显不同, Ag-Al异质纳米球二聚体呈现出在紫外和可见光区的双Fano共振现象。 Ag-Al二聚体表面等离子体互相耦合引起Fano共振从而导致表面等离子体的共振抑制和增强。 研究结果对在紫外-可见光区的表面等离子体应用、 纳米光学器件的设计与开发及基于表面等离子体共振的表面增强光谱、 生物传感和检测研究等有一定参考价值。
Abstract
Metal nanostructure material has attracted great attention due to its surface plasmon resonance. The optical properties of heterodimer metallic nanostructure materials are different compared with that of homogeneous nanostructure materials because their symmetry structure is broken. The symmetry of the original structures will be changed, and the interaction between the two particles will produce Fano resonance. The Fano resonances are the result of the double or more surface plasmon resonances coupling, and be controlled by properly controlling the nanostructures. The electric field enhancement and the radiation characteristics of the nanostructure are further optimized for the Fano resonance controlled. Aluminum nanostructure materials have become the best choice of the surface plasmon resonance in the UV region, because gold, silver and other noble metals have inter-band transition effects. In this work, we study the local field and absorption spectra of heterodimer composed of a silver nanosphere and an aluminum nanosphere by the Finite-Difference Time-Domain (FDTD) theory. Firstly, the effects of the incident polarization, the geometric like, nanospheres separation, nanosphere radius and physical dielectric media on the optical response of silver-aluminum nanospheres heterodimer are analyzed. Secondly, the near field distributions of heterodimer are given in-depth discussion. Due to the destruction of the symmetry of dimer material, heterodimeric optical character is significantly different from homodimer. Fano resonances are produced in UV and visible light in the heterodimer respectively when silver-aluminum nanospheres heterodimer is illuminated by the Y-polarized light. More favorable Fano resonance effects can be obtained by regulating the spacing and size of heterodimer in the given dielectric environment which is also an effect factor certainly. Finally, the absorption of the heterodimer contributed from each nanosphere structure is also analyzed. In this way, the result which is a general and complete description of the optical properties of silver-aluminum nanospheres heterodimer nanostructure in the paper, leads to the suppression and enhancement of the surface plasmon resonance in different frequency bands and may be valuable for the design and development of plasmonic devices and optical tools in UV-visible light and could serve as the basis of the future experimental analysis of surface enhanced spectroscopy, molecular detection and biosensor etc.

程龙, 姜永刚, 黄丽清, 张宇, 吴际, 孙昊, 刘齐, 王军. Ag-Al纳米球二聚体的光学性质研究[J]. 光谱学与光谱分析, 2016, 36(11): 3470. CHENG Long, JIANG Yong-gang, HUANG Li-qing, ZHANG Yu, WU Ji, SUN Hao, LIU Qi, WANG Jun. Optical Properties of Ag-Al Nanosphere Heterodimer[J]. Spectroscopy and Spectral Analysis, 2016, 36(11): 3470.

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