Structural studies of liquid hydrogen fluoride by neutron diffraction

Abstract

Neutron diffraction measurements have been made on liquid DF at 293 K using 0·7 Å neutrons. The intramolecular distance r DF was found to be 0·95 Å in satisfactory agreement with accepted values. The intermolecular contribution has been transformed to give the composite pair correlation function d L(r) and exhibits a well-defined hydrogen-bond at a distance of 1·62 Å. The results are compared with four predictions based on computer simulation with different models for the intermolecular interaction potential. The experimental results discriminate clearly between the four potentials. They favour the HF3 potential [14] but the very simple HFC potential [16] is also satisfactory. Comparison is also made with diffraction data for the solid and vapour phase measurements on HF and DF. The possible formation of cyclic hexamers in the liquid phase is discussed.