Dresden 2020 – wissenschaftliches Programm
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DY 42.8: Vortrag
Mittwoch, 18. März 2020, 17:15–17:30, ZEU 160
Dynamics of Lithium Chloride Solutions in Nanopores of Various Diameters - a NMR Study — •Christoph Säckel, Sarah Schneider, and Michael Vogel — Institut für Physik kondensierter Materie, TU Darmstadt
We analyse ion transport in aqueous salt solutions confined to nanopores as part of a project that aims to develop a new generation of nanosensors by combining the effectiveness of biological ion channels with the robustness of synthetic silica nanopores. To this end it is necessary to understand the influence of the confinement on the temperature-dependent ion transport. We systematically vary the pore parameters and study effects on the dynamics of aqueous LiCl solutions using 2H and 7Li nuclear magnetic resonance (NMR). We combine homogeneous and gradient field NMR to selectively investigate water and ion dynamics on broad time and length scales from room temperature to the supercooled regime. Both the local and long-range dynamics of ions and water show a slowdown in silica confinement. In addition, our data indicates more heterogeneous dynamics for the liquid in confinement than in bulk. Moreover, NMR studies of solutions in functionalized silica pores reveal a significant influence of the chemical nature of the inner pore surfaces. The observed effects can be explained by a slower layer of solution at the pore walls and bulk-like dynamics in the pore centre. Self-diffusion shows an Arrhenius-like behaviour of the solution in confinements, while bulk samples are best described by a VFT fit.