Preparation Of A New Sers Substrate And Spectroscopy Study Of Nitrogen/Sulfur-Containing Molecules In Nano-System

Since it was first discovered that Raman scattering from molecules adsorbed on certain surface was extremely enhanced, surface-enhanced Raman spectroscopy shows high sensitivity for detecting the molecules adsorbed on surfaces of the metals in sub-and monomolecular layers, and presents plentiful optical surface information of the molecular structure. Therefore, the spectroscopy has been widely used in some scientific and technical fields in recent years, such as surface science, qualitative and quantitative analysis, etc. The preparation of the SERS substrate is the key point to initiate and/or broaden novel SERS applications as well as in the understanding of the SERS mechanism.The study of nitrogen/ sulfur -containing organic molecules has been an interesting research subject in the study of SERS. Sulfur atom or nitrogen atom has a strong tendency to be adsorbed on the surfaces of a variety of metals. Such adsorption can result in the formation of well-organized self-assembled monolagers (SAMs) on the surface of metal, which make the metal possess some especial characters. Moreover, the nitrogen/ sulfur -containing organic molecules and metal/ transition metal ion easily form interesting complexes. So these complexes have some especial capabilities, which are used in our everyday lives and science study.In this thesis, a new method of preparing SERS substrate had been proposed with high SERS' activity and three kinds of nitrogen/ sulfur -containing molecules had been studied with SERS in nano-system. A series of meaningful results were obtained: 1. A new SERS-active substrate on the surfaces of a series of electric material was prepared by an electrochemical technique in an aqueous solution of nitrate. The experimental result showed that the substrate having excellent quantlities, demonstrating significant enhancement effect, spatial uniformity and good stability. As the fabrication process of such substrate is very simple and inexpensive, it is proposed that this method may be used to large-scale preparation of the substrates which may have been widely applied in Raman analysis.2. The rotational conformers and adsorption behavior of the L-cysteine molecules adsorbed on gold/silver nanoparticles were studied, and we futher studied the charge transfer between the L-cysteine molecule and the gold electrode surface. The results can provide the experimental gist for using the SERS technology to resolve the problems in biochemistry and biophysics.3. High quality SERS spectrum of PNA had been obtained in colloid solution, on rough electrode and nanoparticles modified electrode system.We studied the adsorption behavior of the PNA adsorbed on the three kinds of substrates and the charge transfer between molecule and electrode surface, which can provide the experimental basic for application.4. In different voitage, the competition behavior of sulfer/nitrogen atom and silver atom was studied. Because the molecule has simple structure, the experiment result has an important role for understanding the mechanism of the SERS by calculating molecular bond polarizability derivatives in different voltage.