Department of Materials Science and Engineering, ‡International Institute for Nanotechnology, and §Department of Chemistry, Northwestern University , Evanston, Illinois 60208 United States.
Nano Lett. 2017 Apr 12;17(4):2313-2318. doi: 10.1021/acs.nanolett.6b05101. Epub 2017 Mar 30.
DNA-programmable assembly has been used to prepare superlattices composed of octahedral and spherical nanoparticles, respectively. These superlattices have the same body-centered cubic lattice symmetry and macroscopic rhombic dodecahedron crystal habit but tunable lattice parameters by virtue of the DNA length, allowing one to study and determine the effect of nanoscale structure and lattice parameter on the light-matter interactions in the superlattices. Backscattering measurements and finite-difference time-domain simulations have been used to characterize these two classes of superlattices. Superlattices composed of octahedral nanoparticles exhibit polarization-dependent backscattering but via a trend that is opposite to that observed in the polarization dependence for analogous superlattices composed of spherical nanoparticles. Electrodynamics simulations show that this polarization dependence is mainly due to the anisotropy of the nanoparticles and is observed only if the octahedral nanoparticles are well-aligned within the superlattices. Both plasmonic and photonic modes are identified in such structures, both of which can be tuned by controlling the size and shape of the nanoparticle building blocks, the lattice parameters, and the overall size of the three-dimensional superlattices (without changing habit).
DNA 可编程组装已被用于制备分别由八面体和球形纳米粒子组成的超晶格。这些超晶格具有相同的体心立方晶格对称性和宏观的菱形十二面体晶体习性，但由于 DNA 长度可调谐的晶格参数，使得人们可以研究和确定纳米结构和晶格参数对超晶格中光物质相互作用的影响。背散射测量和有限差分时域模拟已被用于表征这两类超晶格。由八面体纳米粒子组成的超晶格表现出与由球形纳米粒子组成的类似超晶格的偏振相关背散射相反的偏振依赖性。电动力学模拟表明，这种偏振依赖性主要归因于纳米粒子的各向异性，并且只有当超晶格中的八面体纳米粒子排列良好时才会观察到这种偏振依赖性。在这些结构中都可以识别出等离子体和光子模式，都可以通过控制纳米粒子构建块的尺寸和形状、晶格参数以及三维超晶格的整体尺寸（不改变晶体习性）来进行调谐。
