title: Controlled assembly and plasmonic properties of asymmetric core-satellite nanoassemblies.
abstract: The assembly of noble metal nanoparticles offers an appealing means to control and enhance the plasmonic properties of nanostructures. However, making nanoassemblies with easily modifiable gap distances with high efficiency has been challenging. Here, we report a novel strategy to assemble gold nanoparticles (AuNPs) into Janus-type asymmetric core-satellite nanostructures. Markedly different desorption efficiency between large and small AuNPs in ethanol allows us to prepare the asymmetric core-satellite nanoassemblies in a dispersed colloidal state with near 100% purity. The resulting nanoassemblies have well-defined structures in which a core AuNP (51 nm) is covered by an average of 13 ± 3 satellite AuNPs (13 nm) with part of the core surfaces left unoccupied. Strong surface plasmon coupling is observed from these nanoassemblies as a result of the close proximity between the core and the satellites, which appears significantly red-shifted from the surface plasmon resonance frequencies of the constituting nanoparticles. The dependence of the surface plasmon coupling on a gap distance of less than 3 nm is systematically investigated by varying the length of the alkanedithiol linkers. The asymmetric core-satellite nanoassemblies also serve as an excellent surface-enhanced Raman scattering substrate with an enhancement factor of ~10(6). Finally, we demonstrate that the presented assembly method is extendible to the preparation of compositionally heterogeneous core-satellite nanoassemblies.
authors: Department of Chemistry, Institute of Nanosensor and Biotechnology, Dankook University, 152 Jukjeon-ro, Suji-gu, Yongin, Gyeonggi 448-701, Korea.
authors: Jun Hee
authors: JH
authors: Yoon
authors: Jonghui
authors: J
authors: Lim
authors: Sangwoon
authors: S
authors: Yoon
mesh_terms: D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008968:Molecular Conformation; D010316:Particle Size; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D006046:Gold