Deuteron nuclear magnetic resonance and dielectric study of host and guest dynamics in KOH-doped tetrahydrofuran clathrate hydrate

The host as well as the guest dynamics in ion doped clathrate hydrates were studied via several deuteron nuclear magnetic resonance techniques and using broadband dielectric spectroscopy in conjunction with the application of large electrical fields. At a given temperature evidence for up to three relaxation processes was found for samples with mole fractions larger than 10^-4 KOH. The two slower processes, unraveled via an electrical cleaning procedure, are similar to those detected on undoped samples in which they proceed on slightly longer time scales. The fastest process exhibits a weak temperature dependence except close to the transition into the low-temperature phase. Here, an incomplete proton order is established on the hydrate lattice and a residual orientational motion of the guest molecules could be detected at low temperatures. These results demonstrate the large degree of coupling between host and guest motions.