title: Solvation structure and ion complexation of La3+ in a 1 molal aqueous solution of lanthanum chloride.
abstract: H/D isotopic substitution neutron scattering and X-ray scattering have been used to investigate the short and intermediate range solution structure in a 1 m aqueous solution of lanthanum chloride. To improve the reliability of the local structural information on the cation environment, information has been incorporated from Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy data into the applied analytical framework. The markedly different structural sensitivities of the experimental probes allow the construction of a detailed three-dimensional atomistic model using the Empirical Potential Structure Refinement (EPSR) technique. The results show that at the investigated concentration La(3+) is hydrated by eight water molecules and one chloride ion, forming an inner-sphere ion complex in which the water molecules maintain angular configurations consistent with a tricapped trigonal prism configuration. This local geometry considerably disrupts the bulk solvent structure.
authors.affiliation: Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom.
authors.forename: Sofia
authors.initials: S
authors.lastname: Díaz-Moreno
authors.forename: Silvia
authors.initials: S
authors.lastname: Ramos
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Bowron