A study of the molecular motion in glucose/water mixtures using deuterium nuclear magnetic resonance

Abstract

Using separate samples containing deuterated glucose and D2O, the motions of the glucose and the water molecules in the viscous liquid and in the amorphous glass phase of glucose/water mixtures are examined. Spin-lattice relaxation measurements and spectra obtained in the solid confirm the existence of both a crystalline ice phase and an amorphous glass phase. Diffusion measurements performed using the large gradient in the fringe field of a superconducting magnet determine the rates of translational motion of both the sugar and the water molecules over a limited range of temperature in the viscous liquid region. From the deuterium nuclear magnetic resonance spin-lattice relaxation time, T1, the spin-spin relaxation time, T2, and spin-alignment measurements, correlation times for the motion of these molecules are obtained. The correlation time for the α process increases dramatically at Tg, while the β process continues into the low temperature glass phase, following an approximately Arrhenius relationship.