Molecular conformation in the liquid phase

A brief review is made of methods used to determine the conformation of molecules by diffraction methods. Studies of various simple molecules (e.g. N₂, P₄, CC?₄) show little change of form between the vapour and condensed phases. More recent work on hydrogen-bonded liquids indicates that there is a substantial stretch in the intra-molecular OH(D) bond. Although little data is currently available the results seem to indicate that this effect is systematic for associated species and relates to the strength of the hydrogen bond. The prospects for a more detailed study using the improved flux levels of new X-ray and neutron sources are also examined.