الفهرس 
ExperimentalOnly 14 pages are availabe for public view
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Abstract
The silver nanoparticles (Ag NPs) were prepared by different chemical methods. Moreover, due to the limitation of these chemical methods to control the particle size, we used the laser to photofragment the large size nanoparticles into smaller ones. Furthermore, the absorption and fluorescence spectra were recorded for the prepared Ag NPs having different particle size. The transmission electron microscope photographs have found to be support the optical measurements.
Silver nanoparticles (Ag NPs) were prepared by the normal chemical method and doped with polyvinyl alcohol (PVA). The electrical and optical properties were studied. The band intensities of the FT-Raman spectra were found to increase by increasing the amount of Ag NPs up to 3.6 mg then decreased. The UV-Vis. spectrum for 3.6 mg Ag NPs doped in PVA presented a small red shift and by rising of temperature the band intensity decreases.
Surface-enhanced Raman scattering (SERS) spectra of sodium benzoate (SB) adsorbed on Ag NPs were recorded as a function of particle size of Ag NPs. The carboxylic group bands were enhanced as the particle size decreases due to the chemisorption. The SB bands were enhanced as the coverage density of Ag NPs increased.
Raipo nucleic acid (RNA) bases have a great importance in the biological and genetics applications. The surface-enhanced Raman scattering was used to study the orientation and adsorption structure of RNA bases adsorbed on the surface of silver nanowires (Ag NWs). Many bands were red shifted due to the chemisorption of RNA bases on the Ag NWs surface.
Metal Selenides nanocrystallites (ZnSe, CdSe, and PbSe) of different sizes were also prepared in polyvinyl alcohol (PVA) photopolymer films. Particle sizes were optimized by variation the metal to Se ions ratio up to 16:1 as well as doping in PVA. X-ray diffraction shows the degree of crystallinity of PVA. A decreasing was observed due to the doping with selenide NPs. The UV-Vis absorption spectra for the Selenide NPs in both solutions and PVA films showed blue shifts with increasing the ratio of metal ion leading to the decrease of the Particle size. The Photoluminescence spectra obtained at 441.5 nm He-Cd excitation of (ZnSe, CdSe, and PbSe) in PVA show the same behavior of absorption spectra. A blue shift in most of the FT-IR and FT-Raman bands of PVA was observed due to the interaction between PVA and (ZnSe, CdSe, and PbSe) NPs, which increases by the decreasing of particle size. The conductivity values of PVA were increased by decreasing the particle size of nanoparticles.
The SiO2 NPs, SiO2 NPs coated with Au NPs and Ag NPs, SiO2 NPs coated with Ag NPs, SiO2 NPs coated with Au NPs, Ag+ doped SiO2 NPs, and Au3+ doped SiO2 NPs photocatalyst were used for the photodegradation of methyl red. The kinetic and mechanism of the photocatalytic reactions were studied and accorded well with the experimental results.