Quasi-elastic neutron scattering study of AlCl3 aqueous solution

Quasi-elastic neutron scattering from protons in AlCl₃ aqueous solution has been measured by the use of a triple-axis spectrometer. Assuming the existence of two different kinds of water molecules, either in free state or in bound state, the whole shape of energy spectra of scattered neutrons was analyzed. About eight water molecules were found to be bound to an Al ion, being almost independent of the solute concentration. The diffusion constant, the rest time and the jump length of the remaining free water molecules were estimated based on a jump diffusion model.