Preparation Of Noble Metal Nanoparticles Composite Glass And Research Of Photoelectric Properties

With the development of nanoscience, preparation of nanomaterials and the research of photoelectric properties are becoming more and more important. Noble metals nanoparticles composite glass (noble metal nanoparticles doped silicate glass) have the large third-order nonlinear susceptibility and the ultrafast nonlinear response due to surface plasmon resonance of metal nanoparticles, therefore, it has been widely used in the field of photonics, such as optical data storage, optical waveguide , all optical switches and so on. For all of these applications, the optical properties of noble metal nanoparticles composite glass strongly depend on the size, shape, density and spatial distribution of the metal nanoparticles in the glass matrix. In this thesis, varied noble metal nanoparticles composites glass have prepared successfully, and the effective control on the above characteristics of metal nanoparticles using the subsequent treatment was realized. Specific details of the work as follows:Varied noble metal (gold and silver) nanoparticles composite glasses have been prepared successfully. Three different materials preparation methods have been used to prepare metal nanoparticles of composite glass with different spatial distribution. The gold-doped glass was prepared by using the melting-heat treatment method, and the gold nanoparticles were distributed in the whole sample. The monodisperse gold nanoparticles have been obtained in the slide surface with the aids of ion sputtering method and subsequent heat-treatment. These gold nanoparticles partially embedded in glass matrix. The absorption spectrum of samples reflected the specific absorption peak of gold nanoparticles. Combining the scattering electron microscope (SEM) images of samples prepared under different conditions, the formation mechanism of such monodisperse gold nanoparticles was discussed concretely. The silver nanoparticles composite glass was also obtained by using the methods of silver sodium ion-exchanged and subsequent heat-treatment, and we found the silver nanoparticles just distributed in the surface of glass.Experimental device was designed and produced, and the electric field assisted dissolution (EFAD) of gold rods in silicate glass was realized. Considering influences in the experiment, we designed and fabricated the experimental device of EFAD. And the EFAD of gold rods in silicate glass was realized by this device. The sample surface morphology near the edge of anode region was observed by SEM, and the results show that some gold rods with large aspect ratio dissolved into quasi-spherical nanoparticles, and the others remain elliptical structure. This result is consistent with the sample absorption spectra in this region. The dissolution of the gold particles is attributed to electrons tunneling and the gold cations conductivity basing on the measurement of current-voltage characteristics in EFAD experiment.The directest evidence was provided for the EFAD of gold nanoparticles, and the physical process of EFAD of metal nanoparticles was described clear. With the aids of EFAD technique, the EFAD experiment of samples with gold nanopartilces partially embedded glass, it have been prepared by the gold target sputtering and subsequent heat treatment. From SEM images of the samples after the experiments, it can be seen that some of the original spherical gold nanoparticles are dissolved to lunar-eclipselike structure and even fully dissolved, which left the nano-hole structure in the sample surface. These phenomena provided directest evidence for electric field assisted dissolution of gold nanoparticles.The loop current evolution with time was discussed in detail during the entire experiment. It was found that when the voltage used in the experiments is increasing step-by-step, in the initial of every increase voltage, loop current has a very sharp increase in the current process; then the current will experience a very long slow process of decay maintaining the same voltage value. The initial rapid increase in current suggests that this is the beginning of the electronic transmission, and such electronic transmission of the gold nanoparticles will lead to polarization and ionization. In fact, the long process of current decay is the process of the cathode conductivity of electrons and ions with positively charged gold clusters. In particular, it was pointed out that in the loop current, the contribution of gold cations transfer is the sole cause leading to those gold atoms dissolved into the glass from nanoparticles.The substrates for surface enhanced Raman scattering were prepared successfully. Through controlling the conditions of the sputtering and heat treatment, the silica substrates with a certain surface-enhanced Raman scattering active gold nanoparticles was prepared successfully. Combination of the SEM photographs of the sample surface and gold nanoparticles specific surface plasmon resonance effect, the electromagnetic field enhancement mechanism of such sample surface enhanced Raman scattering was discussed.The femtosecond third-order nonlinear absorption properties of silver nanoparticles composite glass by ion-exchanged method were studied. The femtosecond third-order nonlinear absorption properties of silver nanoparticles were measured by Z scan method with a single beam, with the use of the Ti-sapphire femtosecond laser system with wavelength of 800 nm and pulse width of 120 fs. For the silver nanoparticles, the reverse saturable absorption can be determined from the open aperture normalized transmittance curve shape, and the emergence of reverse saturable absorption can be explained by interband transitions of electron caused by two-photon absorption process.