Browsing by Subject "Electron spectroscopy"
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Item Open Access Characterization of surfaces of various polymers by electron spectroscopy(Elsevier, 1997-06-16) Süzer, S.X-ray induced photo and Auger electron spectroscopic techniques have been used to characterize the surface composition of biaxially oriented polypropylene sheets with and without corona discharge treatment. The surfaces of polypropylene sheets without corona treatment contain very small amounts of 0 and the C 1 s peak is narrow, consisting mainly of -CH groups and less than 5% -C-O groups. After corona treatment the intensity of the 01s peak increases by a factor of 8, the Cls peak broadens and -C-O intensity increases by a factor of 3. The surfaces of aluminized polypropylene contains both aluminium oxide and metallic aluminium. From the measured intensity ratio of the A13’/A10 peaks the thickness of the oxide layer is estimated to be smaller than 4 nm. Aging increases the carbon content of the surface without changing the aluminium oxide/ metal composition. 0 1997 Elsevier Science B.V.Item Open Access Electron spectroscopy and the electronic structure of KNbO3: First principle calculations(Taylor & Francis Online, 2014) Simsek S.; Koc, H.; Trepakov, V. A.; Mamedov, A. M.; Özbay, EkmelThe electronic structures of KNbO3were calculated within the density functional theory, and their evolution was analyzed as the crystal-field symmetry changes from cubic to rhombohedral via tetragonal phase. We carried out electron-energy loss spectroscopy experiments by using synchrotron radiation and compared the results with the theoretical spectra calculated within Density Functional Theory. The dominant role of the NbO6 octahedra in the formation of the energy spectra of KNbO3compound was demonstrated. The anomalous behavior of plasmons in ferroelectrics was exhibited by the function representing the characteristic energy loss in the region of phase transition. © 2014 Copyright Taylor & Francis Group, LLC.Item Open Access Preparation of Au and Au-Pt nanoparticles within PMMA matrix using UV and X-ray irradiation(2009) Ozkaraoglu, E.; Tunc, I.; Süzer, ŞefikAu and Au-Pt alloy nanoparticles are prepared and patterned at room temperature within the PMMA polymer matrix by the action of 254 nm UV light or X-rays. The polymer matrix enables us to entangle the kinetics of the photochemical reduction from the nucleation and growth processes, when monitored by UV-vis spectroscopy. Accordingly, increase of the temperature to 50 °C of the reaction medium increases the nucleation and growth rates of the nanoparticle formation by more than one order of magnitude, due to enhanced diffusion and nucleation at the higher temperature, but has no effect on the photochemical reduction process. Presence of Pt ions also increases the same rate, but by a factor two only. Similar photochemical reduction and particle growth take also place within the PMMA matrix, when these metal ions are subjected to prolonged exposure to X-rays, as evidenced by XPS analysis. Both angle-resolved and charge-contrast measurements using XPS reveal that the resultant Au and Pt species are in close proximity to each other, indicating the Au-Pt alloy formation to be the most likely case.