%0 Journal Article
%T The Radial Distribution Functions of Water as Derived from Radiation Total Scattering Experiments: Is There Anything We Can Say for Sure?
%A A. K. Soper
%J ISRN Physical Chemistry
%D 2013
%R 10.1155/2013/279463
%X The present paper reviews the investigation of ambient water structure and focusses in particular on the determination of the radial distribution functions of water from total experimental radiation scattering experiments. A novel method for removing the inelastic scattering from neutron data is introduced, and the effect of Compton scattering on X-ray data is discussed. In addition the extent to which quantum effects can be discerned between heavy and light water is analysed against these more recent data. It is concluded that, with the help of modern data analysis and computer simulation tools to interrogate the scattering data, a considerable degree of consistency can be obtained between recent and past scattering experiments on water. That consistency also gives a realistic estimate of the likely uncertainties in the extracted radial distribution functions, as well as offering a benchmark against which future experiments can be judged. 1. Introduction The structure of water is a recurring theme in the scientific literature on water and its many manifestations in solutions, mixtures and at surfaces. Being a liquid, water does not have ˇ°structureˇ± in the sense that a crystal or a building has a structure. Nonetheless the forces between water molecules, which prevent molecular overlap and drive hydrogen bonding, give rise to characteristic correlations in space and time between water molecules. These correlations are called the structure of water, the nature of which correlations is a direct result of the forces between molecules. There is no direct way of measuring the forces between water molecules in the liquid, and these forces are different in the condensed state of the liquid compared to between two water molecules which approach each other in vacuo. Hence in principle if we can measure the correlations in the liquid experimentally, we can learn about the nature of the forces between molecules in water, and hence develop some intrinsic understanding about what makes water the rather important and special liquid that it is. Radiation scattering, whether by photons, neutrons or electrons, gives direct insight into these atom scale correlations, providing the radiation has the appropriate wavelength. This, combined with the a seemingly insatiable demand for knowledge about water at all levels of complexity, and from a wide variety of endeavours, including fundamental science, practical physical chemistry, geological situations, biological applications, and industry, has led to a plethora of data on water structure which extends back at least 80
%U http://www.hindawi.com/journals/isrn.physical.chemistry/2013/279463/