Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 89: Metal substrates: Adsorption of organic / bio molecules V

O 89.6: Vortrag

Freitag, 30. März 2012, 11:45–12:00, A 053

The metal/ionic liquid interface: Structure formation and temperature dependent behavior of ionic liquid adlayers on Au(111) — •Benedikt Uhl, Michael Roos, and Rolf Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

Ionic liquids (IL) are promising electrolytes in Li-Ion batteries. The behavior of the IL's at the electrode surface and the properties of the solid-liquid-interface is crucial for the performance of such electrochemical systems, but investigations on this topic are at their very beginning. In this work, we investigated the structure formation during submonolayer growth of the model systems 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide (BMP-TFSA) and 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMIM-TFSA) on Au(111). The resulting structures were characterized with scanning tunneling microscopy (STM) under UHV conditions at temperatures between 100 K and 298 K and at varying IL coverages in the submonolayer regime. At room temperature, the adsorbed IL's form a 2D liquid. At lower temperatures, mobility is frozen and different structures appear. A 2D glassy state and various structures with long range order are detected, depending on the temperature of the substrate during the evaporation process. The 2D crystal structures are influenced by the subjacent Au(111) reconstruction pattern. In addition, the dynamics of the adlayers are investigated during continuous heating from 100 K to room temperature in order to get insight into the thermal stability of the adlayers.