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چكيده انگليسي :

89 Fabrication of Metal and Oxide nanoparticles by laser ablation process Navid Mottaghi n mottaghi@ph iut ac ir Januari 2013 Department of Physics Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language Farsi Supervisor Dr Mehdi Ranjbar ranjbar@cc iut ac ir Assistant Dr Parviz Kameli kameli@cc iut ac irAbstract In this study fabrication of Nickel thin films by pulsed laser deposition process in vacuum environmentwas investigated Nickel thin films were fabricated with different substrate temperatures with Excimer laser KrF248 nm By increasing substrate temperature Nickel thin films started to growth at the surface disorderly in whichthe roughness of thin fimls increased by substrate temperature till 500 but in 700 it decreased and surface ofthin films had a regular shape X ray diffraction XRD showed that in 700 Ni Si 100 single crystals start toepitaxial growth in Si direction Atomic force microscopy AFM showed that these single crystals hadrectangular parallel sides which revealed the growth direction of single crystals Ag NPs also were generated by laser ablation in liquid environment with two differen laser appliances Excimer KrF 248 nm and Nd YAG1064 nm Transmission electron microscopy TEM images revealedcrystallite nanostructers of Ag Ag NPs had a beige color after synthesizing After adding palladium chloride PdCl2 into product of Ag NPs the color of the Ag NPs changes into milky color which suggested the interattionbetween Ag NPs and PdCl2 The evolution of Ag surface plasmon resonance SPR peaks was traced by opticalspectroscopy in 190 1100 nm wavelength range The extinction spectra showeded that plasmonic peak of Ag andabsorption peak of PdCl2 are eliminated after adding PdCl2 X ray photoelectron spectroscopy XPS revealed thepresence of metallic palladium Pd particles which were reduced by adding PdCl 2 into Ag nanoparticles XRDanalysis showed the presence of silver chloride AgCl structures Pd partciles also had visible peaks in spectra TEM images also showed Ag particles are almost polygonal and spherical in shape and FFT showed thecrystalline nature of particles TEM histograms of Ag NPs before and after adding PdCl2 showed an increase inparticle size which refers to reduction and stacking of PdCl2 to Ag NPs The core shell nanostructures were alsodetected by TEM images The XPS spectras revealed the presence of Pd in the Ag PdCl2 solution which showedthe reduction and production of Pd particles Molybdenum Oxide MoO3 NPs were also fabricated by laserablation process by irradiating Molybdenum foil in liquid environments with two different laser appliances Excimer KrF 248 nm and Nd YAG 1064 nm Optical spectroscopy was done in 190 1100 nm range The opticalspectra showed an absorption edge which refers to MoO3 NPs band gap In this study the presence and role ofPdCl2 in MoO3 NPs solution were studied It showeded that by adding PdCl2 into the MoO3 NPs solution theoptical band gap decreased slightly during the aging process TEM images showed that by adding PdCl2 intoMoO3 NPs solution many of the NPs patricles strat to stack and growth inside of each other and also core shellnanostructures were synthesized MoO3 NPs size had an enormous effect on optical band gap because NPs whichwere produced by Excimer laser had a smaller band gap than NPs which were generated by Nd YAG 1064 nm TEM images confirm this matter because NPs which were fabricated by Excimer laser had a bigger size about22 3 nm more than NPs which were generated by Nd YAG 1064 nm so by increasing in NPs size the optical bandgap decreased In this study the liquid environment role was also considered The optical band gap of MoO3 NPswhich were produced in Hydrogen peroxide H2O2 was smaller than MoO3 NPs which were produced indionized water DI The difference between optical band gaps was about 0 9 eV Key Words Pulsed laser ablation vacuum thin films liquid environment surface plasmonresonance core shell nanostructures nanoparticles optical band ga

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ساخت نانو ذرات اكسيدي و فلزي به روش كندوسوز ليزري

لايه هاي نازك , محيط خلا و مايع , بيشينه ي جذب پلاسموني , ساختارهاي هسته پوسته , گاف اپتيكي , PdCl2