Structural and Dynamical Properties of Water Molecules Confined within Clay Sediments Probed by Deuterium NMR Spectroscopy, Multiquanta Relaxometry, and Two-Time Stimulated Echo Attenuation

The structure and multiscale dynamics of water molecules confined within dense clay sediments are investigated by deuterium (²H) NMR spectroscopy, relaxometry, and two-time correlation measurements. The splitting of the ²H NMR resonance line quantifies the specific ordering of water molecules confined within the clay interlamellar space. The angular distribution of clay aggregates within the sediment is evaluated from variation of the transverse ²H NMR relaxation rates as a function of orientation of the clay film within the static magnetic field. The average residence time of the water molecules within clay aggregates is determined by multiquanta spin-locking relaxometry. Finally, water exchange between different aggregates is extracted from the attenuation of ²H two-time stimulated echo. These simultaneous NMR dynamical investigations cover a broad range of characteristic times (between 10 μs and 100 ms) appropriate to investigate the multiscale dynamical behavior of water molecules confined within heterogeneous porous networks