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- Title
Hopping dynamics and diffusion of atoms, molecules, and ions in nanoporous solids by exchange NMR spectroscopy.
- Authors
Selter, Philipp; Schmithorst, Michael B.; Chmelka, Bradley F.
- Abstract
Molecular diffusion in nanoporous materials can be understood as series of dynamic hopping or exchange motions of molecules between different discrete sites. Exchange NMR offers the spectral resolution to distinguish between these different sites, based on isotropic and anisotropic NMR interactions that manifest differences in the local chemical or structural environments of molecules at different sites or their local orientations. Such interactions facilitate the observation of distinct adsorption environments and provide insights on the number and distributions of distinct types of environments and the geometries and motional correlation times of local hopping events between different sites. The temporal range accessible by exchange NMR is governed by the time required for the observation of the NMR signal (< 1 ms) and the return of the nuclear magnetic polarization to thermal equilibrium (typically several seconds). Over such timescales, this permits slow molecular exchange processes between local environments to be probed in great quantitative detail. The resulting insights on dynamic exchange or hopping of atoms, molecules, or ions in nanoporous solids provide a basis for understanding processes that occur over longer length and time scale, which ultimately account for their macroscopic diffusion properties.
- Publication
Adsorption, 2021, Vol 27, Issue 5, p857
- ISSN
0929-5607
- Publication type
Article
- DOI
10.1007/s10450-021-00318-8