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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Charged Soft Matter - organized by Joachim Dzubiella (Albert Ludwigs University Freiburg, Freiburg)

CPP 16.10: Vortrag

Mittwoch, 24. März 2021, 14:20–14:40, CPPa

Local dynamics of ionic liquids studied by ²H NMR — •Elisa Steinrücken, Manuel Becher, and Michael Vogel — TU Darmstadt, Institut für Physik kondensierter Materie, Hochschulstr. 6, 64289, Darmstadt, Germany

Room Temperature Ionic Liquids (RTIL) are molten salts at ambient temperatures with a low vapour pressure. They are usually glass forming systems with complex and heterogeneous molecular dynamics. The combination of different cations and anions opens wide ranges of chemical and physical applications. Hence, a fundamental understanding of molecular dynamics is of crucial importance. Here, RTILs consisting of imidazole-based cations and [Tf2N]⁻ or [BF₄]⁻ anions are in the experimental focus. Nuclear Magnetic Resonance (NMR) provides access to dynamics in wide ranges of time and length scales [M. Becher, E. Steinrücken, M. Vogel, J. Chem. Phys., 2019]. Due to its isotope selectivity the dynamical behaviour of the two components can be distinguished. Performing ²H NMR experiments on selectively deuterated cations, we gain deep insights into their microscopic rotational dynamics. When combining ²H spin-lattice relaxation (SLR) and stimulated-echo (STE) experiments, rotational correlation times of the cation are accessible from the fast motion in the liquid to slow glassy dynamics. Furthermore, we exploit that STE experiments and ²H line-shape analysis provide information about the mechanism for rotational motion. Altogether, we show that application of ²H NMR to RTIL has a high potential for the characterization of time scales and motional mechanisms of the molecular dynamics.