Autor(en): | Beerwerth, Joachim Siegel, R. Hoffmann, Lars Plaga, Lucie S. Storek, Michael Bojer, B. Senker, J. Hiller, Wolf Böhmer, Roland |
Titel: | From ultraslow to extremely fast dynamics in sodium nitrate |
Sonstige Titel: | an 17O NMR study |
Sprache (ISO): | en |
Zusammenfassung: | Increasing dynamics in solids featuring nuclei subjected to second-order quadrupolar interactions lead to central-transition spectra that undergo two consecutive line-shaped transitions. Conventional motional narrowing occurs when the molecular exchange rate is on the order of the strength of the dominant interaction. In a second step, the resulting intermediately narrowed spectra change further when the motion becomes faster than the Larmor precession rate, leading to terminally narrowed spectra that can display a residual quadrupolar shift. We derive analytic expressions for this shift and analyze the quadrupolar central-transition spectra in terms of CN symmetrical cone models. Increasing the number of sites to N ≥ 3, the terminally narrowed spectra remain unaltered, while the intermediately narrowed spectra remain unaltered only for N ≥ 5. This finding relates to the different (cubic vs. icosahedral) symmetries that are required to average out the spatial second- and fourth-rank terms in the second-order quadrupolar interaction. Following recent work (Hung et al., Solid State Nucl Magn Reson 84:14–19, 2017), 17O NMR is applied to examine the three-site rotation of the nitrate group in NaNO3. Line shapes are measured and analyzed, and in addition to prior work, satellite-transition and stimulated-echo experiments are carried out. The final-state amplitudes extracted from the latter are reproduced using model calculations. It is shown how two-dimensional exchange spectra relating to N-site cone motions can be decomposed in terms of effective two-site-jump spectra. This latter approach is successfully tested for NaNO3. |
Schlagwörter (RSWK): | NMR-Spektroskopie Hamilton-Gleichungen Spin-Gitter-Relaxation |
URI: | http://hdl.handle.net/2003/40134 http://dx.doi.org/10.17877/DE290R-22009 |
Erscheinungsdatum: | 2020-05-28 |
Rechte (Link): | https://creativecommons.org/licenses/by/4.0/ |
Enthalten in den Sammlungen: | Experimentelle Physik III |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
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Beerwerth2020_Article_FromUltraslowToExtremelyFastDy.pdf | 1.92 MB | Adobe PDF | Öffnen/Anzeigen |
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