Research Of Surface Enhanced Raman Scattering And Wettability On Several Micro-nanostructured Materials

Micro-nanostructured materials are very important to the renovation and advancement of modern nanotechnology, which have been widely in the field of information, communication, automobile, medicine, biotechnology, analysis, diagnosis, chemistry, manufacture and environment protection. Surface enhanced Raman scattering (SERS) and wettability properties of materials are related with their micro-nanostructures, so the research of SERS and wettability on micro-nanostructured materials will have attracted more and more attention in the future. In this thesis, we study the SERS and wettability on several micro-nanostructured materials, including metal and semiconductor/metal composites:(1) A simple method of the reduction of AgNO3 by copper foil in aqueous medium was used to prepare silver dendrites, which can be used as a novel good reproducible SERS active substrate. The SERS spectra of 4-pyridinethiol on this novel substrate reflected the different SERS activities on the minuteness and strong Ag dendrites. The electromagnetic coupling enhancement and chemical enhancement mechanisms are used to explain the SERS effect. We are sure that it is a powerful analytical tool of determining chemical information for compounds.(2) The study of SERS for semiconductor nanoparticles are very important to extend the application of SERS and explore the deeply information of semiconductors. However, the SERS for semiconductors is very weak. In this section, SERS of 4-mercaptopyridine (4-Mpy) adsorbed on the surface of TiO2 nanofibers coated with Ag nanoparticles and ZnO/Ag composite microspheres were obtained. The SERS enhancement mechanisms have also been studied.(3) We prepared ordered two-dimensional arrays of patterns with silver nanoparticles immobilizing on the patterned self-assembled monolayers (SAM) of alkanethiolates on gold, which can be used as a hierarchical SERS substrate. SERS spectra and surface enhanced Raman mapping of 4-pyridinethiol SAM on this novel SERS active substrate were also investigated. The different SERS activities were observed on the surface of hierarchical micro-nanostructure. The enhancement factor was well studied and the electromagnetic enhancement mechanism was used to explain the SERS effect.(4) We report a simple wet-chemical method to prepare silver microflowers and large spherical particles. The controlling of the silver microstructures can be achieved only by adjusting the concentration of the reactants. It is found that the large spherical silver particles exhibit superhydrophilic properties, microflower-like silver particles exhibit highly hydrophobic properties. The Raman spectrum of large spherical silver particles was studied. (5) Here we report a remarkably straightforward method for preparing large scale superhydrophobic substrate which yields robust double roughness metal surface coatings and which is carried out under ambient conditions using readily available starting materials and laboratory equipment. The method uses electroless galvanic deposition to coat a metal substrate with a textured layer of a second metal.