Studies On Suface Enhanced Raman Scattering In Nanoparticles Modified Electrode System

Surface Enhanced Raman Scattering (SERS) is a powerful and sensitive instrumental tool for obtaining detailed information of adsorbed molecules, such as the adsorption configuration of molecules and the interaction mechanism of the molecules with the surface of the substrate. And Spectroelectrochemistry has been a new technology for studying the electrochemistry system. It is well known that potential is an important factor influencing surface adsorption and reaction. The adsorption behavior of the adsorbate on the substrate would be greatly affected by the surface configuration of the adsorbate and the applied electrode potential in electrochemically system. At the same potential, if the surface configurations of adsorbates are different, the adsorption patterns of the adsorbates may be different though the composing of them is same. At different applied potential, the adsorption behaviors of the same adsorbates are also probably different.In SERS optical spectroscopy, the noble metal Ag nanoparticles can serve as a highly efficient substrate for SERS investigation, but in prevenient reports, the SERS substrates, such as Ag nanoparticles, were prepared by chemical reduction methods, these methods are simple and rapid, and the enhanced effects of SERS are are very obvious. In addition, the laser compositing method can well control nanoparticles' uniformity and the scale in the preparing process, it be well used widespread in many fields.The nanoparticles modified electrode is the artificial designed manufacture surface, so this electrode had the unusual effect and the latent application value that has brought many research about this. With the nanotechnology development, the nanoparticles modified electrode as an important part of nanotechenology, is growing rapidly.In this paper, we modified the Ag electrode with the silver nanoparticles, which prepared by chemical reduction methods and the laser compositing method. And we found that this electrode is a more sensitive SERS substrate than silver nanoparticles and the roughen electrode by ORC method. Thus, we obtained the high quality SERS spectra of Piperidine, a set of Pyridinemolecules under low concentration. Furthermore, we analyzed the adsorption configuration of molecules combined with the Density Functional Theory (DFT). We believed that the nanoparticles modified electrode can using for single molecule detection.Employing photons as probes, Raman spectroscopy is potentially an ideal technique for studying chemical structures and physical interface phenomena. The photons with ultraviolet (UV) frequency have high energy, which could induce resonance or near resonance transitions between electron energy levels of molecules. Moreover, UV Raman can avoid the fluorescence. Due to those merits of UV Raman, we have obtained high-quality surface Raman spectra of Thymine on roughened Au surface, which are difficult to be observed at NIR or visible excitation. We found that the UV-SERS of Thymine is potential dependent, with the applied potential shift, the relative intensities of most bands changed obviously. We considered that Charge transfer effect between the molecule and the Au atom could probably contribute to the experimental results.