A differential anomalous X-ray scattering study and reverse Monte Carlo simulation of a highly concentrated solution of zinc bromide in water

A differential anomalous X-ray scattering (DAS) study of the structure of a highly concentrated aqueous solution of zinc bromide (19.5 molal) is presented Synchrotron radiation was used for four diffraction experiments at photon energies of 12500 eV, 13462 eV (Br-K-edge) and 9000 eV, 9650 eV (Zn-K-edge) The dispersion corrections were calculated from the photoabsorption coefficients determined by absorption experiments. The differential structure factor and its Fourier transform, the differential atom pair correlation function, were obtained after an intricate data evaluation procedure The technique of the Reverse Monte Carlo simulation, which requires no intermolecular potential as input, was used to elucidate the microscopic structure of zinc bromide solution, which resembles the crystal structure of ZnBr2 . H2O, in which the zinc ion is coordinated tetrahedrally with two bromine ions and two water molecules.