Study of Ni(II) coordination in aqueous solution by EXAFS analysis

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been applied to the study of water coordination of the Ni(II) ion in aqueous solution. High resolution x-ray spectra were measured for Ni(NO3) ⋅6H2O salt and its 0.1M aqueous solution using a synchrotron radiation source. Analysis of the spectra by Fourier transform reveals first sphere coordination in agreement with x-ray diffraction results. In addition, a second coordination sphere is detected and a tentative distance from the Ni(II) ion to the second sphere water molecules of 3.2±0.1 Å is measured.