A two-dimensional deuterium nuclear magnetic resonance study of molecular reorientation in sugar/water glasses

摘要

Two-dimensional nuclear magnetic resonance time domain analysis of the stimulated echo experiment is used to study the molecular reorientation of deuterated glucose molecules in a glucose/water glass at about 15 deg C above the glass transition. By measuring both the cos-cos and sin-sin two-time single particle correlation functions it is shown that the reorientation is isotropic, which enables the determination of the relaxation time T_(1Q) and the rotational correlation time. By fitting the cos-cos and sin-sin correlation functions with a modified Kohlrausch-Williams-Watts (KWW) function and comparing the resulting parameters with simulations, it is shown that the reorientation is dominated by small angle jumps (= 3 deg), but there is also a small fraction of large angle (= 34 deg) jumps present.