Browsing by Author "Ataman, O. Y."

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    X-ray photoelectron spectroscopic characterization of Au collected with atom trapping on silica for atomic absorption spectrometry
    (Sage Publications, Inc., 1997) Süzer, Ş.; Ertaş, N.; Kumser, S.; Ataman, O. Y.
    The nature of analyte species collected on a cooled silica tube for atom-trapping atomic absorption spectrometric determination was investigated with the use of X-ray photoelctron spectroscopy (XPS). An XPS spectrum of gold deposited on atom-trapping silica tubes reveals a Au 4f7/2 peak with a binding energy of 84.8 (±0.2) eV, which falls in the middle of the binding energies corresponding to zerovalent Au(0) at 84.0 eV and that of monovalent Au(I) at 85.2 eV. The corresponding energy for Au vapor deposited on silica is also 84.8 eV. Deposition of AuCl4- solution on silica results in two different Au 4f7/2 peaks with binding energies of 84.8 and 87.3 eV corresponding, respectively, to Au(0) and Au(III). Deposition of the same AuCl4- solution on platinum metal again gives two peaks, this time at 84.4 and 87.0 eV energies corresponding again to Au(0) and Au(III). Combining all these data, we conclude that gold is trapped on atom-trapping silica surface as zerovalent Au(0) with a 0.8-eV matrix shift with respect to the metal surface. A similar 0.6-eV shift is also observed between the binding energy of 4f7/2 Hg22+ measured in Hg2(NO3)2·2H2O powder and that deposited on silica.
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    XPS characterization of Bi and Mn collected on atom-trapping silica for AAS
    (Sage Publications, Inc., 1999) Süzer, Şefik; Ertas, N.; Ataman, O. Y.
    The chemical state of analyte species collected on a water-cooled silica tube during atom-trapping atomic absorption spectrometric determination is investigated with the use of X-ray photoelectron spectroscopy (XPS) for Bi and Mn. Analysis of the Bi 4f7/2 peak reveals that the chemical state of Bi is +3 during initial trapping (before the atomization stage), but an additional 0-valence state of Bi is also observed after the atomization stage. With the use of the measured Mn 2p3/2 binding energy together with the observed 3s multiplet splitting, the chemical state of Mn is determined as +2 in all stages. Together with our previous determination of 0 valence for Au, it is now postulated that the stability of certain valence states of the three elements (Au, Bi, and Mn) on the silica matrix can be correlated to their electrochemical reduction potentials.