Low-Q neutron diffraction from supercooled D-glycerol

Abstract

Neutron diffraction measurements of the structure factor of supercooled liquid D-glycerol are reported for the range 0·03 ≲ Q ˇ- 4·0Å^-1 at temperatures between 300 and 175 K. We find that the structure is essentially unchanged over this entire range. We expected some evidence of increased hydrogen bonding at the lower temperatures, but no direct evidence for any strong orientated density-density correlation at low-Q due to a hydrogen bond is observed. To provide a contrast, the structure factor of vanadium pentafluoride is discussed briefly because vanadium pentafluoride is known to form fluorine-fluorine bridges in the dense state. We equate loosely this bridging with a hydrogen bond. In that compound there is evidence for F-F bridging at low-Q. Small angle Placzek corrections to the D-glycerol scattering cross section data are estimated.