Self-assembly Of Au Monolayer Structures At The Liquid/liquid Interface And Their Optical Properties Researches

Interfacial assembly is a phenomenon that nanoparticles absorb at two-phase interfaces and form thin films with particular structures, such as gas-liquid and liquid-liquid interfacial assembly, which is the most commonly method for assembly of nanoparticles into 2-dimensional nano-film. In this thesis, dependent on the characteristics of slightly solubility of n-butanol into water, a series of gold nano-films with different nanostructures were assembled at the n-butanol/water interface. The as-prepared gold nanoparticle film was examined by TEM, HR-TEM (High Resolution Transmission Electron Microscope), UV-visible spectrum and SERS (Surface Enhanced Raman Scattering). The main research contents are summarized as follows:(1) Self-assemlby of gold nanoparticles into monolayer at n-butanol/water interfaces.n-butanol was used as an inducer reagent. By changing the way to remove n-butanol after nanoparticles has been arrested by the interface, two types of patterns were obtained as closed-packed and chain-like structures. By controlling aging time, Gold nanoparticles in the monolayer gradually fused each other, and finally close-packed and chain-like structures completely transformed into a network and wire-like structure, respectively. These phenomena of structural conversion are attributed to strong capillary forces existing at the interface and Ostwald Ripening propcess.(2) Influence of toluene on the nanostructure of gold nanoparticle monolayer formed at the n-butanol/water interface. In order to gain different nano-film structures, toluene was used to mix with n-butanol to change the surrounding of interfacial nanoparticle. Toluene as one of romatic compounds is well-known to have the ability of transferring the surface charge of gold nanoparticles by conjugative effect, and consequently changing the dielectric constant of oil phase. Thus, interfacial gold nanoparticles can fuse together with a rapid speed, and wire-like nanostructures were directly fabricated without aging. The larger volume ratio of toluene to ethanol caused gold nanoparticles in chain-like nanoparticle monolayer to fuse to a greater degree, and the chain length of chain-like structure depended on the added volume of n-butanol. When the amount of toluene was fixed, the more the amount of n-butanol in the mixture of toluene and n-butanol is, the shorter the chain length is and vice versa.(3) SERS properties of close-packed gold nanoparticle monolayers prepared at n-butanol/water interfaces. The close-packed gold nanoparticle monolayer and their fusion structures were used to explore the relationship between SERS spectra and nanostructures, reveal the crucial factors of SERS enhancement. The results indicate that, under the present unoptimizable conditions, the SERS enhancement on the close-packed gold nanoparticle monolayer is more intense than that on other fusion structure due to the existent of plenty of 2-3 nm interparticle spacing, which is ascribed to the electromagnetic coupling between gold nanoparticles.