Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 31: Poster Session II

DS 31.9: Poster

Thursday, March 15, 2018, 11:15–13:15, Poster F

Well Ordered Iron Sulfide Layers on Au(111) — •Earl Davis, Giulia Berti, Helmut Kuhlenbeck, and Hans-Joachim Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft

The iron-sulfur world hypothesis of G. Wächtershäuser is an origin-of-life theory which proposes that early life may have formed at the surface of sub-marine iron sulfide compounds. This involves the activation of carbon dioxide to form simple organic molecules. Theoretical and experimental studies have shown that the mineral greigite (Fe₃S₄) should be active for this.

With the goal of CO₂ activation, our aim was to prepare ordered iron sulfide layers. We found that such a layer can be prepared on Au(111) by deposition of iron in an atmosphere of S₂ molecules which are produced by an electrochemical sulfur source. According to XPS, the layer is sulfur terminated, and STM shows a homogeneous, well-ordered surface with a hexagonal symmetry. The same symmetry is found in LEED patterns and the hexagonal lattice parameter fits to what is expected for Fe₃S₄(111). I/V LEED curves were measured in order to determine details of the structure. Additionally, initial reactivity experiments have shown that it is possible to hydrogenate the surface, which might offer routes to hydrogenation reactions.