Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: P1: Interfaces and Thin Films
CPP 15.14: Poster
Montag, 16. März 2015, 16:00–19:00, Poster A
Molecular scale structures of ionic liquid interfaces under electric potential — •Julian Mars1, Peter Reichert1, Kasper Skov Kjaer2, Tim Brandt van Driel2, Martin Meedom Nielsen2, Moshe Deutsch3, and Markus Mezger1,4 — 1Max Planck Institute for Polymer Research, Mainz, Germany — 2Centre for Molecular Movies, Department of Physics, TechnicalUniversity of Denmark, Lyngby, Denmark — 3Department of Physics and Institute of Nanotechnology andAdvanced Materials, Bar-Ilan University, Ramat-Gan, Israel — 4Johannes Gutenberg-Universität Mainz, Germany
Electrolyte interfaces under electric potential are of a great scientific and technological interest. For diluted electrolyte solutions, the interfacial ion profile can be described by the Gouy-Chapman theory. However, for solvent-less electrolytes such as ionic liquids the diluted solution approximation is clearly invalid. Despite of their importance, the molecular scale structure of ionic liquids near electrodes is still under debate. We have studied the potential dependent interfacial structure of room temperature ionic liquids with high-energy x-ray reflectivity and impedance spectroscopy measurements. We find oscillatory charge density profiles consisting of alternating anion- and cation-enriched layers at both cathodic and anodic potentials. This structure is shown to arise from the same ion-ion correlations dominating the liquid bulk structure. The relaxation dynamics of the interfacial structure were studied by impedance spectroscopy and time resolved x-ray reflectivity experiments with sub-millisecond resolution.