A neutron scattering study of the structure of amorphous glucose

Wide angle neutron scattering combined with H/D substitution has been applied to determine the hydrogen bond structure in glassy and liquid glucose [C6H7O(OH)(5)]. H/D substitution involved only the H atoms belonging to OH groups. The resulting radial distribution function g(HH)(r) clearly shows the ordering of H atoms, in a way expected from hydrogen bonding. At -10 degrees C and 35 degrees C, at which temperatures glucose is in the glassy state, temperature dependence of the hydrogen bond structure is clearly observed. The number of hydrogen bonds in the glassy state is similar to that in the crystalline state. At 80 degrees C, in the undercooled liquid state, the number of hydrogen bonds is 20% lower and the hydrogen bond structure much less pronounced. The hydrogen bond H-H distance is found to be in the range of 2.4-2.6 Angstrom, similar to the values found in the crystal (2.40 Angstrom) and water at room temperature (2.44 Angstrom). At the lower temperatures, preliminary GROMOS molecular dynamics simulation results of g(HH)(r) are in reasonable agreement with the experimental data. However, at 80 degrees C, the simulations seriously overestimate intermolecular structure. (C) 1997 American Institute of Physics.