Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.40: Poster

Wednesday, March 28, 2012, 18:15–21:45, Poster B

STM investigation on the adlayer structures of the ionic liquids EMIM-TFSA and BMP-TFSA on Au(111) in the submonolayer regime — •Benedikt Uhl, Michael Roos, and Rolf Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

The adlayer structures of the ionic liquids (IL) 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide (BMP-TFSA) and 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMIM-TFSA) on Au(111) have been investigated by scanning tunneling microscopy (STM). Especially the structure of the first layer of adsorbates on the metal surface is under investigation. The measurements were performed in ultra high vacuum (UHV) at temperatures between 100 K and 298 K, with coverages in the submonolayer and the monolayer regime. At temperatures around 100 K the BMP-TFSA as well as the EMIM-TFSA adsorbates appear as round shaped protrusions in the STM pictures. The nature of these protrusions, which may represent cations, anions or both of them, is discussed. Depending on the preparation process, the adsorbates form different structures, a 2D glass-like phase as well as 2D crystalline structures with long-range order. The different structures are presented in detail (2D density, unit cell) and their dependence on surface coverage is elucidated. The 2D crystalline structures show strong dependence on the Au(111) reconstruction pattern. In this context the influence of the substrate on the structure formation is discussed.