To characterize the structural relaxation of an aqueous solution of LiCl, frequency-dependent shear rheological experiments are carried out near its glass transition. Analyzed within the fluidity representation, the generic spectral shape that was previously found for a range of different kinds of glass formers is confirmed for the currently studied hydrogen-bonded fluid as well. Furthermore, the validity of the rheological equivalent of the Barton-Nakajima-Namikawa relation is demonstrated for the aqueous LiCl solution. Its mechanical response is compared with that obtained using dielectric spectroscopy, a technique which is sensitive to both the reorientational dynamics of the water molecules and the translational dynamics of the ionic species. The extent to which these electrical polarization processes are coupled to those governing the viscoelastic response is discussed, also in comparison with the behavior of other ion conducting liquids.

Using oxygen-17 as a nuclear probe, spin relaxometry was applied to study the high-density and low-density states of amorphous ice, covering temperatures below and somewhat above their glass transitions. These findings are put in perspective with results from deuteron nuclear magnetic resonance and with calculations based on dielectrically detected correlation times. This comparison reveals the presence of a wide distribution of correlation times. Furthermore, oxygen-17 central-transition echo spectra were recorded for wide ranges of temperature and pulse spacing. The spectra cannot be described by a single set of quadrupolar parameters, suggesting a distribution of H–O–H opening angles that is broader for high-density than for low-density amorphous ice. Simulations of the pulse separation dependent spin-echo spectra for various scenarios demonstrate that a small-step frequency diffusion process, assigned to the presence of homonuclear oxygen–oxygen interactions, determines the shape evolution of the pulse-separation-dependent spectra.

In this work, trimethoxyboroxine (TMB) is identified as a small-molecule glass former. In its viscous liquid as well as glassy states, static and dynamic properties of TMB are explored using various techniques. It is found that, on average, the structure of the condensed TMB molecules deviates from threefold symmetry so that TMB’s electric dipole moment is nonzero, thus rendering broadband dielectric spectroscopy applicable. This method reveals the super-Arrhenius dynamics that characterizes TMB above its glass transition, which occurs at about 204 K. To extend the temperature range in which the molecular dynamics can be studied, 11B nuclear magnetic resonance experiments are additionally carried out on rotating and stationary samples: Exploiting dynamic second-order shifts, spin-relaxation times, line shape effects, as well as stimulated-echo and two-dimensional exchange spectroscopy, a coherent picture regarding the dynamics of this glass former is gained.

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.

Highly ordered D2O ice XIV is identified as a possible new candidate phase for ice XX (PNP-ice XX) on the basis of calorimetry, dielectric relaxation spectroscopy, powder X-ray diffraction, and volumetric measurements. Previous work yielded weakly ordered deuterated ice XIV featuring less than 20% of the maximum order defined in terms of Pauling's configurational entropy. Here, we introduce a preparation protocol that allows for highly ordered ice XIV, with a degree of order between 40% and 65%. This protocol involves 110 minutes of annealing of doped ice XII at 94 K and 0.81 GPa, followed by recovery to ambient pressure and storage in liquid nitrogen. The use of both DCl-doping to produce ionic and Bjerrum defects as well as the addition of 1% H2O to produce dynamic H-defects in the bath of D-atoms are key for accelerating the ordering process. At 94 K the dielectric relaxation of highly ordered ice XIV is about ten times slower than that of weakly ordered ice XIV. By contrast to weakly ordered ice XIV, the dielectric relaxation times of highly ordered D2O ice XIV feature a clear kink near the transition to ice XII at 102 K. Furthermore, the volume changes by about 0.6% at the transition of ice XII to ice XIV, owing to the impact of H-ordering on the O-atom network. Powder X-ray diffraction on highly ordered D2O ice XIV reveals several Bragg peaks splittings that are not resolved in weakly ordered ice XIV. These superstructure reflections indicate the presence of a new crystallographic phase and call for powder neutron-diffraction studies to fully elucidate the crystal structure of highly ordered ice XIV.