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O: Fachverband Oberflächenphysik

O 31: Poster: Organic Molecules on Inorganic Substrates

O 31.3: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster C

Orientational transition of dimolybdenum tetraacetate on Au/Cu(111) — •Alexei Nefedov¹, Thomas Strunskus², Maria Brzhezinskaya³, Martin Anstett⁴, Benjamin Stadtmüller⁴, Martin Aeschlimann⁴, and Angelika Kuehnle⁵ — ¹Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany — ²University of Kiel, Kiel, Germany — ³Helmholtz-Zentrum Berlin fuer Materialen und Energie, Berlin, Germany — ⁴University of Kaiserslautern, Kaiserslautern, Germany — ⁵University of Bielefeld, Bielefeld, Germany

Dimolybdenum tetraacetate (MoMo) adsorbed on metal single crystal surfaces shows a partial transition from an ordered close-packed upright standing configuration (chain phase) to a low-packed phase upon cooling (mesh phase). On the base of DFT calculations it is supposed that this phase consists from flat lying molecules. In order to confirm upright/flat orientation of the MoMo molecules in different phases NEXAFS spectroscopy was applied. The MoMo layer of different (0.1-1 ML) coverages were evaporated on the Au/Cu(111) substrate both at room and low temperatures. XPS/NEXAFS measurements were carried out at deposition temperature as well after cooling or/and warming the sample. After NEXAFS experiments it was found that a molecule coverage also plays very important for the transition. Moreover, it was established that, in addition to thermodynamics, kinetic processes may play a crucial role in this process as well.

Keywords: structural transition; NEXAFS spectroscopy; coverage dependence