Fabrication, Characterization, And Optical Activity Of New SERS Substrates

Owing to their special structure, metal nanoparticles show special performance and have great application potential, thus more and more people have intensive interest on it. One of the optical properties of metal nanoparticles- surface plasma resonance has long been one of the key issues in the field of nanoscience.We can adjust the position of surface plasma resonance wavelength by controlling structure, shape and size. In recent years, with the development of nanotechnique, nanoscience has taken an important step from simplex preparation of nanomaterials to investigation of property, assembly and enlarge the application of nanomaterials. Surface-enhanced Raman scattering (SERS) is one of selective surface enhanced-effect. SERS fundus of active metal nanoparticle has great effect. Surface-enhanced Raman scattering (SERS) is, in nature, a particle size dependent optical phenomenon of metals,it dependent on the nature of metals,structure of metals(size,shape,spacing of nanoparticles).Therefore,Controlling the size and shape of nanoparticles is very important in the SERS field.The present researches mainly focus on the optical property of metal nanoparticles. We make nanoparticles to be used in research of SERS by controlling the size and shape of nanoparticles.The results are outlined as follows:1,We report an electrolyte-mediated method for improved dense deposition of 1-3 nm gold nanoparticles/seeds on 3-aminopropyl trimethoxysilane-functionalized silica nanoparticles. When electrolyte is added into gold seed colloids above the critical coagulation concentration, it will to compress the electric double layer thickness of the charged seeds. This compression allows particles to approach each other more closely via the well-known"electrostatic screening"effect and easily leads a dense particle deposition. Inductively coupled plasma, UV-vis spectroscopy, and transmission electron microscopy were used to characterize the deposition process, and confirmed the expected, improved dense seed deposition. Gold nanoshells with continuous gold shell were prepared from the resulting gold seed-deposited silica nanoparticles and used as a substrate for surface-enhanced Raman scattering. 2,We used nanoparticles with tunable surface plasmon resonance (SPR), for example Au nonorods (NRs), as the cores to fabricate the core?shell nanoparticles as improved transition metal substrates for SERS.3,We made Au@Ag@Au multilayer nanoshell nanoparticles using Sodium citrate as SERS active metallic fundus.4,We report self-assembly of charge-stabilized gold and silver nanoparticles at water-air and water-oil interfaces, via manipulation of the interactions between the interfaces and the adsorbing nanoparticles. Nanoparticle adsorption from bulk colloids to an interface is an energy-favored, but finite sorption barrier-restrained (kinetics-controlled) process. Hydrophobic coatings and organic solvents consequently decrease the sorption barrier, facilitate nanoparticles overcoming the sorption barrier, and mediate the self-assembly of nanoparticles.