Neutron and X-ray scattering studies of hydration in aqueous solutions

The presence of ions and/or apolar species in water provides a rich and var ied environment in which many natural processes occur. This review provides results of recent structural studies of aqueous soluti ons derived from state-of-the-art neutron and X-ray scattering methods. The enhanced resolution provided by methods such as neutron diffraction and is otopic substitution. and anomalous X-ray diffraction, have given scientists new insights into the contrasting hydration structures of a variety of ion s and small molecules, and crucially into how these structures might affect the general properties of solutions. The discussion points out common feat ures of ionic hydration within particular series, such as the alkalis, hali des and transition metals, and also indicates where significant differences in hydration structure appear.