Preparation Of Silver Micro-nano Structures And Their Surface-enhanced Raman Scattering Properties

In the past decades, silver nanoparticles have been the subjects of a numbers of fundamental and practical studies, due to its specially physical and chemical properties. Under irradiation of lights with a proper frequency, the surface plasmon in silver particles can be excited, as a result, the local electromagnetic field close to the particles can be greatly enhanced. This is the foundation of Surface-enhanced Raman scattering (SERS) spectroscopy techniques that sensitive to the electromagnetic fields. Recently, SERS techniques have been used to detect the signs of single molecule. The SERS properties of silver nanoparticles are strongly dependent on the shape, size, and structure of the particles. In this dissertation, controlled synthesis of silver nanoparticles and SERS properties are the main content was studied, the three main parties are following:(1) Aqua-solution method is one of the most common method of inorganic chemical synthesis. Flower-like silver micro-nano materials were successfully prepared by ascorbic acid reduces silver nitrate in aqueous solution with the aid of sodium citrate. By studying the morphology and surface structure of the products, and the morphology of intermediate products, its growth mechanism was proposed. The effects of sodium citrate and pH value on the flower-like silver micro-nano materials were studied. The products deposited on silicon were used as SERS substrates to detect 10-8 M Rhodamine 6G (R6G) molecules, and the enhancement factor reached 4.1×107.(2) In order to simulate the conditions of mineral formation, the hydrothermal method was invented. When using organic solvents instead of water, a new chemical synthesis method: solvothermal was invented. In the inorganic controlled synthesis, polyvinylpyrrolidone (PVP) are frequently used organic agent. In the experiments, PVP not only plays the role of stable nanoparticles, but also plays the role of capping agent. Hydrochloric acid plays an important role in the formation of the cube silver nanoparticles, as without HCl or sulfuric acid instead of hydrochloric acid, cannot obtained the cube silver nanoparticles. We evaluated the SERS properties of the cube silver nanoparticles dispersed on Si wafer using Rhodamine 6G (R6G) as target molecule.(3) porous alumina film is a good template for preparation of nanomaterials, on the basis of previous experience, 6-fold rotational symmetric porous anodic aluminum oxide film was prepared by the optimized anodic oxidation. Use porous anodic aluminum oxide film as template, silver nanowires array was prepared by the method of the alternating current deposition. We evaluated the SERS properties of the silver nanowires array using R6G as target molecule.