Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 24: Metal substrates: Structure, epitaxy and growth (joint session with O)

DS 24.5: Vortrag

Mittwoch, 18. März 2015, 11:30–11:45, MA 042

Comparative study of the carbide-modified surfaces C/Mo(110) and C/Mo(100) using high resolution x-ray photoelectron spectroscopy — •Christoph Gleichweit, Udo Bauer, Max Amende, Stefan Schernich, Oliver Höfert, Jörg Libuda, Hans-Peter Steinrück, and Christian Papp — Lehrstuhl f. Physikal. Chemie II

We present a comparative study of the carbide-modified surfaces C/Mo(100) and C/Mo(110) using synchrotron-based high-resolution x-ray photoelectron spectroscopy (HR-XPS), with the objective of elucidating the differences and similarities of the two crystal facets depending on the C/Mo ratio. We are interested in changes at the surface due to exposure to carbon and oxygen right at the temperature sufficient to drive carbon into the interstitial sites of the Mo lattice. Carburization by dosing ethylene, i.e. carbide preparation, and subsequent oxidative carbon removal by dosing O₂ at 1200 K is followed in great detail through careful analysis of the C 1s, Mo 3d and O 1s core levels. We show that the thin carbide overlayers show spectroscopic differences compared to the thick carbides obtained at high carbon dose. Furthermore we show that the carbide thickness on Mo(110) influences the adsorption properties towards H₂ and CO, pointing towards the importance of the surface structure for reactivity.