A deuteron NMR study of the tetrahydrofuran clathrate hydrate - Part I: Relaxation pathways

Longitudinal H-2-relaxation rates 1/T-1 of the polycrystalline clathrate hydrates THF-h(8).17D(2)O and THF-d(8).17H(2)O have been recorded at 55.3 MHz over the temperature range 20 K to 250 K. In spite of the generally dominating intramolecular quadrupolar relaxation mechanism of the deuteron, intermolecular dipolar contributions to relaxation have been observed. The effect is most obvious for the lattice-forming D2O molecules which become immobile at lower temperatures while the guest molecules still perform fast reorientations.