The hydration structure of Br- from anomalous x-ray diffraction

The method of anomalous x-ray diffraction (AXD) was applied to an aqueous s olution of 6 molal RbBr in water Data were gathered at two wavelengths belo w the absorption edge of Br-. Corrections were made for attenuation, inelas tic scattering and background and container scattering. The corrected data were renormalized and put on an absolute scale of electron units. Fourier t ransformation of these results provided information on the Br- hydration. I t is found that the Br-O nearest neighbour distance is 3.4 Angstrom and the first coordination shell contains between 6 and 7.5 water molecules. There is no evidence to suggest any longer range hydration structure.