| Interest in metal nanoparticles and nano-films stems mainly from their size-dependent physicochemical properties, making them potential candidates for a wide variety of applications in nonlinear optics, mechanics, magnetics, electrics, catalyzer and sensor.The purposes of this dissertation are to study the preparation of Ag nanoparticles, Au nanoparticles and Ag nano-films by photochemical, chemical and electrochemical techniques. By means of characterization methods with TEM, SEM, XPS, XRD, UV-vis, IR and SERS, the influencing factors, growth mechanism and related properties of these metal nano-materials have been investigated.PVP and TSC used as soft-templates, spherical Ag nanoparticles were prepared by chemical reduction. PVP is superior in controlling the particle diameter of Ag nanoparticles to TSC. The results show that PVP firstly coordinates Ag+, then PVP adsorbs in the surface of Ag particles so that prevents Ag particles from growing and reuniting.For the first time, preparation of Ag nanoparticles with non-spherical shape has been conducted from spherical Ag nanoparticles by photoinduced conversion. Triangular and foursquare Ag nanoparticles were respectively obtained in the presence of TSC or PVP. These non-spherical Ag nanoparticles are single-crystals. The fundamental analysis and discussion about the changing causes of nanoparticles shape from spherical to non-spherical have been carried out in photoinduced process. The Ag nanoparticles were prepared by illuminated PVP-AgNO3 aqueous solution. The process of the Ag+ photo reduction follows guise first order reaction. Both the reduction mechanism of Ag+ and the stabilization mechanism of Ag nanoparticles have been presented.Au nanoparticles were prepared by sodium citrate reduction method. The results show that the increase of TSC results in the decrease of the particle diameter of Au nanoparticles and the improvement of monodispersity of Au nanoparticles. The particle diameter of these nanoparticles will become bigger when them are irradiated by photo, but their diameter does not change in the presence of PVA or PVP. The particle diameter of Au nanoparticles becomes smaller when sodium citrate-tannin are used as reducing agent.In-situ preparation of spherical silver nanoparticles(10~30 nm), triangular and hexangular single silver crystal(200~2000 nm) have been conducted in linear Chitosan films by photochemical reduction. The monodispersed spherical silver nanoparticles(5~8 nm) were also electrochemically obtained in the film. By means of characterization with TEM, SEM, IR Spectra and XRD, the fundamental analysis and discussion about the changing causes of silver crystal structure from multi crystal to single crystal have been carried out in photochemical reduction process. The cause lies in the function of both the change of coordinating stability and the photo irradiation.Ag nano-films were obtained by electroless deposition method through induction of stearic acid mono-Langmuir-Blodgett film at air/solid interface or stearic acid monolayer at air/solution interface. The results showed that the pH of sub-phase had an important effect on the microscopic structure of the Ag film, then the cause of which was theoretically analyzed and computed. The possible growing mechanism of silver deposition on monolayer was preliminarily discussed. A novel method fabricating Ag nano-film has been presented, by which we may control the surface microstructure of silver film easily.These Ag films prepared on stearic acid monolayer were used as SRES-active substrate, on which the surface-enhanced Raman scattering spectrum of stearic acid monolayer was obtained for the first time. Moreover, the SERS activity of the Ag film fabricated on mono-Langmuir-Blodgett films was investigated by pyridine as the probe, which strongly indicated their potential application in SERS substrate materials. It was found that stearic acid monolayer vertically adsorbed in the surface of Ag films by analyzing the SERS spectrum of stearic acid monolayer.
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