Schneider, Sarah ; Säckel, Christoph ; Brodrecht, Martin ; Breitzke, Hergen ; Buntkowsky, Gerd ; Vogel, Michael (2020)
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, 153 (24)
doi: 10.1063/5.0036079
Article, Bibliographie
This is the latest version of this item.
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.
| Item Type: | Article |
|---|---|
| Erschienen: | 2020 |
| Creators: | Schneider, Sarah ; Säckel, Christoph ; Brodrecht, Martin ; Breitzke, Hergen ; Buntkowsky, Gerd ; Vogel, Michael |
| Type of entry: | Bibliographie |
| Title: | NMR studies on the influence of silica confinements on local and diffusive dynamics in LiCl aqueous solutions approaching their glass transitions |
| Language: | English |
| Date: | 22 December 2020 |
| Publisher: | AIP Publishing |
| Journal or Publication Title: | The Journal of Chemical Physics |
| Volume of the journal: | 153 |
| Issue Number: | 24 |
| DOI: | 10.1063/5.0036079 |
| Corresponding Links: | |
| 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. |
| Uncontrolled Keywords: | Molecular dynamics, Mesoporous material, Nuclear magnetic resonance, Glass transitions, Larmor precession, Diffusion, Electrolytes, Silicates |
| Identification Number: | Art.No.: 244501 |
| Additional Information: | Supplementary Material: https://t1p.de/347w2 |
| Divisions: | 05 Department of Physics 05 Department of Physics > Institute for condensed matter physics (2021 merged in Institute for Condensed Matter Physics) 05 Department of Physics > Institute for condensed matter physics (2021 merged in Institute for Condensed Matter Physics) > Molekulare Dynamik in kondensierter Materie 05 Department of Physics > Institute for Condensed Matter Physics 05 Department of Physics > Institute for Condensed Matter Physics > Molecular dynamics of condensed matter 07 Department of Chemistry 07 Department of Chemistry > Eduard Zintl-Institut 07 Department of Chemistry > Eduard Zintl-Institut > Physical Chemistry |
| Date Deposited: | 02 Feb 2021 08:28 |
| Last Modified: | 31 Jul 2024 10:31 |
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Available Versions of this Item
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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)
- NMR studies on the influence of silica confinements on local and diffusive dynamics in LiCl aqueous solutions approaching their glass transitions. (deposited 02 Feb 2021 08:28) [Currently Displayed]
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