Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 62: Glasses and Glass transition (joint session DY/CPP)

DY 62.2: Talk

Friday, April 5, 2019, 10:15–10:30, H19

Ion and Molecule Transport in Nanopores - a NMR Study — •Christoph Säckel, Sarah Schneider, and Michael Vogel — TU Darmstadt, Institut für Festkörperphysik, Hochschulstr. 6, 64289, Darmstadt, Germany

We analyze ion and molecule transport in aqueous salt solutions confined to nanopores as part of a project that aims to develop a new generation of nanosensors by combining biological and synthetic nanopores. While biological ion channels are highly selective and sensitive, they lack the robustness for technological applications. In contrast, silica pores are well-established in industrial environments, but possess inferior capabilities, e.g. no selectivity. A hybrid system would combine the favourable properties of both types of pores. It is therefore necessary to understand the influence of the confinement on the temperature-dependent ion and molecule transport. We systematically vary the pore parameters and study effects on the dynamics with ¹H, 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 in the supercooled regime. Both the local and long-range dynamics of ions and water show a slowdown with decreasing pore size. In addition, our data indicates more heterogeneous dynamics for the liquid in confinement than in bulk. Both the slowdown and heterogeneity 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.