Synthesis Of Noble Metal Nanorice And Study On Its Surface Plasmon Properties

In addition to the excellent properties of general nanomaterials,the metal nanomaterials have their own unique optical properties,so it have significant application prospects in ultrasensitive monitoring,new functional materials,chemical biosensors,information storage and so on.Therefore,studying the optical properties of metal nanomaterials is a very important field in nanomaterials.Surface plasmon polariton(SPP)is the collective oscillation of free electrons on the surface of the metal under the action of the external electromagnetic field.This collective oscillation has very novel optical properties,and it also promotes the development of nanomaterials.With the rapid development of nanotechnology and the in-depth study of the surface plasmons,the surface plasmons have developed rapidly into a new subject,and have a wide range of applications in materials,physics,chemistry and energy.SPP is a non radiation electromagnetic wave,which is formed when the incident photon is coupled with the electrons of the metal surface.It would decay exponentially when its propagation direction is perpendicular to the metal surface.When the size of metal is small to the sub wave length,the electromagnetic wave would become local surface plasmons(LSPs)rather than continue to propagate.When the frequency of the incident light is a certain value,the phenomenon of local surface plasmon resonance(LSPR)appears.The kind of resonance can redistribute the electromagnetic field in the nanostructures and produce a huge electromagnetic field enhancement.Surface enhanced Raman scattering(SERS)is based on metal nanostructures electromagnetic field enhancement effect,which is used to strengthen the extremely weak Raman scattering signals,and the enhancement factor could reach 10~4-10~8 and even higher.Another application example of based-surface plasmons is plasmon driven surface catalysis(PDSC).Because SPP is much influenced by the structure,morphology and particle size of the metal,various metal nanoparticles are prepared by various experiment means.In this paper Ag nanorices were synthesized by reduction of polyol,and then various Au-Ag alloy nanorices were synthesized by the galvanic replacement reaction between gold and silver.Experiment results show that the mentioned synthetic method is simple and nanorices with uniform size,controllable morphology and good dispersion could be obtained.With the aid of UV visible absorption,dark field scattering spectrometer and COMSOL simulation,the resonance absorption and scattering properties of the synthetized nanorice structures are studied.The results show that the synthetized rice structures has a very good surface plasma resonance(SPR)performance in the UV-visible band in experimentally and theoretically.Moreover,we can regulate and control the resonance function from UV to NIR by changing the displacement reaction conditions.At the same time,the Raman spectroscope was used to demonstrate the feasibility of the rice structure as the SERS enhanced substrate.Rhodamine6G(R6G)and methylene blue(MB)were used as probe molecules to study the enhancement effect of Ag and Au-Ag hollow alloy rice with the help of systematic mapping measurements,and the results show that the structure of nanorice has strong and uniform enhancement effect.What's more,the hollow alloy nanorice has strong chemical stability,confirmed by the result that the alloy nanorice kept six months performs an excellent enhancement effect.The PATP molecules were also used to study the PDSC reaction of the rice structure.The results showed that the single Ag nanorice or Au-Ag alloy hollow nanorice could drive the PATP molecules to catalyze the formation of DMAB molecules,and have a strong polarization dependence on the SERS and PDSC.When the polarization direction of the excited luminescence is perpendicular to the long axis of the nanorice,the enhancement effect of SERS and the effect of PDSC were most obvious.