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Nuclear dipole interactions in solid Xe-129 measured with NMR
This thesis describes nuclear magnetic resonance experiments on hyperpolarized Xe-129. With spin exchange optical pumping on rubidium it is possible to enhance the Xe-129 spin polarization to five orders of magnitude above its thermal equilibrium. This allows for experiments on small samples, like f...
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| Format: | Dissertation |
| Langue: | anglais |
| Publié: |
Philipps-Universität Marburg
2015
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| Accès en ligne: | Texte intégral en PDF |
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| Résumé: | This thesis describes nuclear magnetic resonance experiments on hyperpolarized Xe-129. With spin exchange optical pumping on rubidium it is possible to enhance the Xe-129 spin polarization to five orders of magnitude above its thermal equilibrium. This allows for experiments on small samples, like films on metal substrates.
During this graduation the installation of a new polarization apparatus was completed. With it, it is possible to create mixtures of Xe-129 with other gases. Mixtures with spin-less Xe-132 are of particular interest, because they allow the manipulation of nuclear dipole-dipole interactions through a variation of the distance.
The line shape of solid Xe-129 nuclear magnetic resonances is dominated by dipolar effects. Since an analytical calculation of the resonance shape is impossible, the moments may be used instead. The parameter dependencies of the first three moments on the polarization and the mixing ratio are quantum mechanically calculated and then verified in experiments. To extract the moments from experimental data a product fit function is introduced, and a determination of the polarization from the skewness of the resonance line is discussed.
The dipole-dipole interaction is also responsible for spin diffusion, which plays an important role in the relaxation. A thin xenon film on a copper substrate may be used as a model system to investigate spin diffusion in a quasi-1d system.
If the dipole-dipole interaction is entirely suppressed by dilution, it is possible to observe annealing effects in the frozen xenon mixture. |
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| DOI: | 10.17192/z2015.0358 |