Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)

O 27.98: Poster

Dienstag, 24. März 2009, 18:30–21:00, P2

Surface Structure of Imidazolium Based Ionic Liquids — •Manuela Reichelt, Tobias Hammer, and Harald Morgner — Wilhelm-Ostwald Institute for Physical and Theoretical Chemistry, University of Leipzig

The focus of our research interest is the investigation of the composition and molecular structure of liquid surfaces with spectroscopic methods (e.g., XPS, UPS, MIES) and the correlation of this information with macroscopic properties of solutions (e.g., surface tension). One of our most powerful techniques is Neutral Impact Collision Ion Scattering Spectroscopy (NICISS) that uses the energy loss of Helium projectiles being backscattered from soft matter targets.

During the last years an increasing research interest in ionic liquids (ILs) took place. ILs are salts that are fluid below 100°C and show numberless possible combinations of cations and anions. However, the physico-chemical behavior of ILs is still not completely understood. Additionally, the knowledge of the molecular surface structure and the surface composition of ILs is necessary for understanding chemical reactions at the surface (e.g., the mechanism of catalysis).

In the presented work we combined NICISS and XPS to investigate the elemental surface composition, elemental concentration depth profiles of the near surface area and the molecular surface structure of two homologous series of imidazolium based ILs. While the kind of anion namely hexafluorophosphate and bis(trifluoromethylsulfonyl)imide was fixed, respectively, the alkyl chain length of the cation was varied to analyze their influence on the properties under study.