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

Two-dimensional nuclear magnetic resonance time domain analysis of the stim ulated echo experiment is used to study the molecular reorientation of deut erated glucose molecules in a glucose/water glass at about 15 degrees C abo ve the glass transition. By measuring both the cos-cos and sin-sin two-time single particle correlation functions it is shown that the reorientation i s isotropic, which enables the determination of the relaxation time T-1Q an d the rotational correlation time. By fitting the cos-cos and sin-sin corre lation functions with a modified Kohlrausch-Williams-Watts (KWW) function a nd comparing the resulting parameters with simulations, it is shown that th e reorientation is dominated by small angle jumps (approximate to 3 degrees ), but there is also a small fraction of large angle (approximate to 34 deg rees) jumps present. (C) 1999 American Institute of Physics. [S0021-9606(99 )51547-X].