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    Investigation of thickness dependence on electronic structures of iron and nickel thin films by L-edge X-ray absorption spectroscopy
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014) Akgul, Guvenc; Akgul, Funda Aksoy; Ufuktepe, Yuksel
    We have studied the effect of the film thickness on the electronic structure of pure nickel and iron thin films. Series of the thin films were evaporated by e-beam evaporation on SiN substrates. The electronic structure of the thin films was investigated using X-ray absorption near edge structure (XANES) spectroscopy. We have showed the thickness dependent variation of the experimental branching ratio (BR) and full-width at half-maximum (FWHM) at the L-3 and L-2 edges for both thin films. A strong thickness dependence of the L-2,L-3 BR and FWHM was found. We have also focused on the deviation of L-3 to L-2 ratio from its statistical value. The average L-3/L-2 white-line intensity ratio was calculated to be 3.4 and 3.0 from peak height and integrated area under each L-3 and L-2 peaks, respectively for iron. Additionally, a theoretical L-2,L-3 edge calculation for nickel was presented. The obtained results were consistent with the general view of the L-2,L-3 BR and FWHM of iron and nickel transition metals. (c) 2013 Elsevier Ltd. All rights reserved.
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    Structural and electronic properties of SnO2
    (ELSEVIER SCIENCE SA, 2013) Akgul, Funda Aksoy; Gumus, Cebrail; Er, Ali O.; Farha, Ashraf H.; Akgul, Guvenc; Ufuktepe, Yuksel; Liu, Zhi
    Highly transparent polycrystalline thin film of SnO2 (tin dioxide) was deposited using a simple and low cost spray pyrolysis method. The film was prepared from an aqueous solution of tin tetrachloride (stannic chloride) onto glass substrates at 400 degrees C. A range of diagnostic techniques including X-ray diffraction (XRD), UV-visible absorption, atomic force microscopy (AFM), scanning electron microscopy (SEM), and synchrotron-based X-ray photoelectron spectroscopy (XPS) were used to investigate structural, optical, and electronic properties of the resulting film. Deposited film was found to be polycrystalline. A mixture of SnO and SnO2 phases was observed. The average crystallite size of similar to 21.3 nm for SnO2 was calculated by Rietveld method using XRD data. The oxidation states of the SnO2 thin film were confirmed by the shape analysis of corresponding XPS O 1s, Sn 3d, and Sn 4d peaks using the decomposition procedure. The analysis of the XPS core level peaks showed that the chemical component is non-stoichiometric and the ratio of oxygen to tin (O/Sn) is 1.85 which is slightly under stoichiometry. (c) 2013 Elsevier B.V. All rights reserved.