Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

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

O 121.8: Talk

Friday, March 20, 2020, 12:30–12:45, TRE Phy

Potential and distance dependent measurements of tunneling barrier-heights at the interface of gold(111) in ionic liquids — •Marcel Lang and Rolf Schuster — Karlsruher Institut für Technologie, Deutschland

The structure of the solid-liquid interface of ionic liquids on charged surfaces depends on the cell potential. E.g. multi-layered structures are found at polarization negative of the pzc.

To investigate these structures perpendicular to an Au(111) electrode we measured the distance dependence of the tunneling current, from which we calculated the local tunneling barrier-heights in four different ionic liquids ([BMP][TFSI], [BMP][FSI], [EMIM][TFSI], [EMIM][FSI]). The measurements were performed using a STM under inertgas atmosphere operating at room temperature.

The measured tunneling barrier-heights are very low at positive potentials. At positive to moderatly negative potentials we observed an almost linear increase in tunneling barrier-height with increasing distance. At more negative potentials (<- 0.9 V vs Pt) strong variations of the tunneling barrier-heights were observed. These variations of the tunneling barrier-heights can be correlated to the local electron density, indicating the formation of up to 3 layers, consisting of alternating kation and anion enriched layers.