基于自组装密排金纳米球微球壳的米散射特性  

Mie Scattering Characteristics of Microsphere Shells Based on Self-Assembled Dense-Packed Gold Nanospheres

作　　者：宋明霞 虞应 刘绍鼎[1] Song Mingxia;Yu Ying;Liu Shaoding(College of Electronic Information and Optical Engineering,Taiyuan University of Technology,Taiyuan O30024,Shanci,China)

机构地区：[1]太原理工大学电子信息与光学工程学院,山西商太原030024

出　　处：《光学学报》2024年第14期326-335,共10页Acta Optica Sinica

基　　金：国家自然科学基金(11804408);山西省基础研究计划(202203021221080)。

摘　　要：通过乳化自组装方法制备了由密排金纳米球所构成的微球壳结构,实验测量及数值计算的单颗粒散射光谱表明,微球壳结构的光学响应与等效高折射率电介质球壳类似,能够产生电偶极及磁偶极共振模式。当两者的相互作用满足Kerker条件时,可形成定向的前向散射,从而有效抑制背向散射。同时,由于金纳米颗粒之间的等离激元耦合作用,微球壳的壳层内部相对电介质结构能够产生更大的局域场增强。此外,通过测试和计算结果的对比可见,随着微球壳尺寸的增大,其壳层厚度有逐渐增大的趋势,同时如环形电偶极、电四极、磁四极等高阶米散射贡献也可有效被激发。上述结果表明这种金纳米球所构成的微球壳是一种具有丰富米散射特性的结构,在增强光学非线性和光学成像等领域具有潜在的应用前景。Objective In recent years, due to the localized surface plasmon resonance properties of noble metal nanoparticles, they have been widely employed in various optical devices. Meanwhile, dielectric nanostructures with high refractive index are also considered potential candidate materials for high-performance optical devices. However, both metal and dielectric nanostructures have their limitations, which restrict the performance of optical devices. According to the equivalent medium theory, superlattices composed of densely packed noble metal nanoparticles can be equivalent to these dielectric materials, thus providing an opportunity for combining the excellent characteristics of both. Previous studies mainly focus on the optical properties of two-dimensional layered structures and three-dimensional solid spheres, core-shell, and coreisland structured superlattices. However, there are no reports on the optical response of self-assembled microsphere shell structures composed of noble metal nanoparticles. Therefore, we focus on the optical response of microsphere shells formed by the self-assembly of gold nanoparticles, demonstrating their rich Mie scattering characteristics. This structure is of great significance for more effective light control and high-performance optical devices.Methods In the experiment, we first synthesize monodisperse and uniformly sized gold nanoparticles using a seedmediated growth method. Subsequently, we employ a two-step ligand exchange method to coat thiol-terminated polystyrene(PS-SH) onto the surface of the gold nanoparticles. Finally, we prepare the microsphere shell structure using the emulsion self-assembly method. During the emulsification, we employ toluene gold nanosphere suspension with a concentration of 60 nmol/L as the oil phase, while the aqueous phase contains a solution of Pluronic?F-108 with mass fraction of 1%. To characterize the morphology of the microsphere shell, we observe the microsphere shell structure and the arrangement of gold nanoparticles on the microsphere

关 键 词：米散射 金纳米球 乳化自组装 等效介质理论 表面等离激元 

分 类 号：O436[机械工程—光学工程]