Deciphering Ni isotope fractionation at Fe-oxides surfaces

We will study the interactions of Ni ions with iron oxides goethite and maghemite-magnetite solid solutions (Fe3-dO4) in aqueous solution, as well as the impact of natural organic matter on these interactions. We make the hypothesis that adsorption of Ni2+ on different Fe-oxides (or its adsorption on specific crystal faces of a given mineral) will lead to surface complexes with different structures. Because isotope fractionation is sensitive to the local chemical environment and bond distances in the formed complexes, this may affect the fractionation of Ni isotopes, which could be used as a tracer in environmental studies. Here, we propose a Ni K-edge HERFD-XAS on FAME-UHD to determine the local environment of Ni at Fe-oxide surfaces, which is otherwise very challenging to perform on lower resolution beamlines because of the close energies of Ni and Fe K-edges