Intermolecular structure of liquid deuterium: A new neutron-diffraction investigation

The static centre of mass structure factor of liquid deuterium, already determined by means of time of flight neutron diffraction (as reported in Physical Review E in 1993), has been re-investigated with a two-axis diffractometer at a reactor source. A detailed analysis of the data is presented, with special attention devoted to the correction for inelastic scattering effects. The comparison of the two sets of data reveals the presence of discrepancies, which cannot be attributed to statistical inaccuracies. The density and the temperature derivatives of the structure factor have also been measured with high accuracy. For these quantities, the two experiments are in good agreement with each other. This suggests that the discrepancy in the structure factor is due to systematic effects which vanish in a differential measurement.