Preparation And Application In Raman Spectra About Two Nanoparticles Materials

Surface-enhanced Raman scattering （SERS） spectroscopy with high sensitivity high selectivity, lossless explorations and adjustable point has been widely used. At present, the SERSactive materials of SERS are mainly restricted to some precious metals （such as: Ag, Au, Cu）and transition metal （Pt, Pd, Fe, Co） and so on. And it is rarely reported that semiconductormaterials can be used as the SERS substrate. As the SERS active substrate, semiconductormaterials with nanoparticles have not only broadened SERS materials, but also have greatsignificance on developing the SERS mechanism. Recently, our research group has observedSERS on different kinds of semiconductor materials （such as CdTe, Pb3O4, ZnO and TiO₂）,and has greatly verified charge transfer model of “semiconductor-to-molecule”.In this paper, two semiconductor nanoparticles materials（SnO₂and ZrO₂） have beenprepared by sol-hydrothermal method, and characterized by the means of SEM、TEM、XRD、Raman and XPS.The results show that,the radius was minor, the particle size was uniform andthey were spherical shape for all of prepared SnO₂and ZrO₂nanoparticles. Especially forSnO₂nanoparticles, its radius is to reach2-3nm, this is because of the Zn2+Mixed with in thesynthesis, it effectively prevented SnO₂particles to grow up, and improved the SnO₂nanoparticles surface defect levels. We determined the SERS activity about the newlyprepared SnO₂and ZrO₂nanoparticles decorated with4-mercaptobenzoic acid, and foundtheir activity as SERS substrate very strong. We found that the particle size of thesemiconductor nanoparticles materials and surface defect levels directly effect their ownSERS activity by the analysis and researchment to the change of SERS signal strength about4-mercaptobenzoic acid molecules decorated in SnO₂and ZrO₂nanoparticles, and found notthe smaller radius is, the better SERS activity is. This is quite helpful for us to research theenhancement mechanism of semiconductor nanoparticles materials as SERS substrate. Inorder to further research the influence of stimulate wavelength to SERS signal strength, werespectively used488,514and633nm stimulate line as inspiring light. Resultly, and not thestronger the inspiring light energy, the better SERS signal is, but when inspiring light energymatch semiconductor nanoparticles energy and adsorption molecule energy, the best effectwill appear. And we also found that no matter what kind of stimulating line, Change rule ofSERS signal strength is consistent, this well proved again when semiconductor nanoparticles is as the SERS substrate, their diameter and surface defect levels directly influence SERSenhancement effect.