Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 121: Solid-Liquid Interface IV: Structure and Spectroscopy

O 121.7: Talk

Friday, March 20, 2020, 12:15–12:30, TRE Phy

Comparative AFM and STM study of the ionic liquid [C1C1Im][Tf2N] on Au(111) from 110 K to Room Temperature — •Manuel Meusel, Matthias Lexow, Afra Gezmis, Andreas Bayer, Florian Maier, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany

Ionic liquids (IL) have raised increased interest in surface science due to their low vapour pressure and the unique possibility to investigate liquid systems using UHV methods. For catalytic concepts involving thin layers of ionic liquids (SCILL and SILP), the understanding of the IL/solid and IL/gas interface is crucial. Therefore, we investigated the adsorption behaviour of [C1C1Im][Tf2N] deposited on Au(111) via AFM and STM from 110 K to room temperature (RT). While it was easier to obtain high sub-molecular resolution images with STM, AFM provided a more stable imaging, especially over the micrometer scale. At 110 K, we observe a closed wetting layer (WL) of anions and cations, showing up two different appearances: a striped and a hexagonal pattern. We assign these two patterns to different molecular orientations resulting in different superstructures. Around 200 K, transitions between both superstructures occur but none of them is dominant after further annealing. Even at RT the molecular ordering of the WL is still present, however the superstructures have vanished.

M.M., M.L. and H.P.S. thank the European Research Council (ERC) for financial support of this research in the context of an Advanced Investigator Grant to H.P.S (No. 693398-ILID).