Schneider, Sarah ; Säckel, Christoph ; Brodrecht, Martin ; Breitzke, Hergen ; Buntkowsky, Gerd ; Vogel, Michael (2023)
NMR studies on the influence of silica confinements on local and diffusive dynamics in LiCl aqueous solutions approaching their glass transitions.
In: The Journal of Chemical Physics, 2020, 153 (24)
doi: 10.26083/tuprints-00024229
Artikel, Zweitveröffentlichung, Verlagsversion
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Kurzbeschreibung (Abstract)
We use ¹H, ²H, and ⁷Li NMR to investigate the molecular dynamics of glass-forming LiCl-7H₂O and LiCl-7D₂O solutions confined to MCM- 41 or SBA-15 silica pores with diameters in the range of d = 2.8 nm–5.4 nm. Specifically, it is exploited that NMR experiments in homogeneous and gradient magnetic fields provide access to local and diffusive motions, respectively, and that the isotope selectivity of the method allows us to characterize the dynamics of the water molecules and the lithium ions separately. We find that the silica confinements cause a slowdown of the dynamics on all length scales, which is stronger at lower temperatures and in narrower pores and is more prominent for the lithium ions than the water molecules. However, we do not observe a temperature-dependent decoupling of short-range and long-range dynamics inside the pores. ⁷Li NMR correlation functions show bimodal decays when the pores are sufficiently wide (d > 3 nm) so that bulk-like ion dynamics in the pore centers can be distinguished from significantly retarded ion dynamics at the pore walls, possibly in a Stern layer. However, we do not find evidence for truly immobile fractions of water molecules or lithium ions and, hence, for the existence of a static Stern layer in any of the studied silica pores.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2023 |
| Autor(en): | Schneider, Sarah ; Säckel, Christoph ; Brodrecht, Martin ; Breitzke, Hergen ; Buntkowsky, Gerd ; Vogel, Michael |
| Art des Eintrags: | Zweitveröffentlichung |
| Titel: | NMR studies on the influence of silica confinements on local and diffusive dynamics in LiCl aqueous solutions approaching their glass transitions |
| Sprache: | Englisch |
| Publikationsjahr: | 2023 |
| Ort: | Darmstadt |
| Publikationsdatum der Erstveröffentlichung: | 2020 |
| Verlag: | American Institute of Physics |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | The Journal of Chemical Physics |
| Jahrgang/Volume einer Zeitschrift: | 153 |
| (Heft-)Nummer: | 24 |
| Kollation: | 13 Seiten |
| DOI: | 10.26083/tuprints-00024229 |
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/24229 |
| Zugehörige Links: | |
| Herkunft: | Zweitveröffentlichungsservice |
| Kurzbeschreibung (Abstract): | We use ¹H, ²H, and ⁷Li NMR to investigate the molecular dynamics of glass-forming LiCl-7H₂O and LiCl-7D₂O solutions confined to MCM- 41 or SBA-15 silica pores with diameters in the range of d = 2.8 nm–5.4 nm. Specifically, it is exploited that NMR experiments in homogeneous and gradient magnetic fields provide access to local and diffusive motions, respectively, and that the isotope selectivity of the method allows us to characterize the dynamics of the water molecules and the lithium ions separately. We find that the silica confinements cause a slowdown of the dynamics on all length scales, which is stronger at lower temperatures and in narrower pores and is more prominent for the lithium ions than the water molecules. However, we do not observe a temperature-dependent decoupling of short-range and long-range dynamics inside the pores. ⁷Li NMR correlation functions show bimodal decays when the pores are sufficiently wide (d > 3 nm) so that bulk-like ion dynamics in the pore centers can be distinguished from significantly retarded ion dynamics at the pore walls, possibly in a Stern layer. However, we do not find evidence for truly immobile fractions of water molecules or lithium ions and, hence, for the existence of a static Stern layer in any of the studied silica pores. |
| Freie Schlagworte: | Molecular dynamics, Mesoporous material, Nuclear magnetic resonance, Glass transitions, Larmor precession, Diffusion, Electrolytes, Silicates |
| ID-Nummer: | 244501 (2020) |
| Status: | Verlagsversion |
| URN: | urn:nbn:de:tuda-tuprints-242299 |
| Zusätzliche Informationen: | Supplementary Material: https://t1p.de/347w2 |
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 530 Physik 500 Naturwissenschaften und Mathematik > 540 Chemie |
| Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Physik Kondensierter Materie (IPKM) 05 Fachbereich Physik > Institut für Physik Kondensierter Materie (IPKM) > Molekulare Dynamik in kondensierter Materie 07 Fachbereich Chemie 07 Fachbereich Chemie > Eduard Zintl-Institut 07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Physikalische Chemie |
| Hinterlegungsdatum: | 17 Jul 2023 08:23 |
| Letzte Änderung: | 31 Jul 2024 10:31 |
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- NMR studies on the influence of silica confinements on local and diffusive dynamics in LiCl aqueous solutions approaching their glass transitions. (deposited 17 Jul 2023 08:23) [Gegenwärtig angezeigt]
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