Experimental determination of the site-site radial distribution functions of supercooled ultrapure bulk water

Neutron diffraction data on three isotopically substituted samples of liquid water in the supercooled regime are presented. Supercooling of ultrapure water has been achieved by means of a polytetrafluoroethylene coating on a standard vanadium sample container. Supercooling water to T=267 K, with density rho=100.2 atoms/nm(3), at ambient pressure gives a shift of the first peak of the three partial structure factors toward lower wave numbers, while the second peak of the oxygen-oxygen partial structure factor moves outwards compared to ambient water. The present data in Q space are compatible with previous x-ray experiments performed on supercooled water. Moreover the partial radial distribution functions obtained here for the first time for the bulk liquid at this thermodynamic state compare well with previous experiments performed at higher pressure. (C) 2002 American Institute of Physics.