Applications Of SERS In The Study Of Absorbed Behavior And Structure Changes Of Molecules On The Surface Of Silver

SERS was used in the study of absorbed behavior and structure changes of molecules on the surface of silver with silver nanoparticles as substrates.1. The environment of the assembly may largely influence the properties of the advanced structure. Herein, the silver/4-aminothiophenol/silver(Ag/PATP/Ag) structures are constructed to generate nanosized metal/molecule/metal junctions via layer-by-layer assembly technique. The effect of the environment, such as adsorption of molecules on the junctions, on the properties of the molecular junctions is investigated by surface-enhanced Raman scattering of the PATP molecules interconnected in Ag/PATP/Ag junctions. It is demonstrated that the modification of molecules such as n-octanethiol, 1,8-octanedithiol, thiophenol 1,4-benzendithiol, and 4-mercaptopyridine, shows negligible effect on the enhanced electromagnetic field arising from the plasmon coupling of neighboring silver nanoparticles. The contributions from photoinduced charge transfer(CT) between the silver nanoparticles through the interconnected PATP molecules could be altered by the modification of the molecules. The large influence from the aromatic thiolsis ascribed to the delocalization of the free electrons in the metal nanoparticles to the conjugated structure of the modified molecules.2. Surface-enhanced Raman scatting(SERS) of 4-Mercaptophenylboronic acid(4-MPBA) was measured on silver nanoparticles(AgNPs) assembled on slides. The SERS study revealed that the adsorbed orientation of 4-MPBA changes regularly with the deprotonation process of 4-MPBA, when p H value changing from 1.0 to 13.0. Furthermore, we found that accompanying the deprotonation process, a self-condensation of 4-MPBA were simultaneously happened, both of which shared the same characteristic spectra except the different stabilities. To the self-condensation reaction, the existence of hydroxyl ions is beneficial. But the self-condensation reaction is an interference reaction to the capture of sugars or glycoproteins with 4-MPBA, widely used in analytical field. Therefore neutral condition is considered optimal for the linkage of sugars and 4-MPBA which is verified under the condition of pH 7.0. In this experiments, a much bigger changes of relative intensity of SERS spectra of 4-MPBA was obtained in pH 1.0 buffer solution than in glucose solution, which can be helpful to those experiment in which the relative intensity of SERS spectra of 4-MPBA is used as a quantitative basis.3. Through controlling the time of anodic oxidation and widening we prepared anodized aluminum(AAO) template with different depths and pore sizes. After being sputterred a layer of sliver at bottom of the AAO, it was applied to surface-enhanced Raman scattering(SERS)...