THEORETICAL-ANALYSIS OF X-RAY-ABSORPTION NEAR-EDGE STRUCTURE OF TRANSITION-METAL AQUEOUS COMPLEXES IN SOLUTION AT THE METAL K-EDGE

We present a detailed analysis of x-ray absorption near-edge structure spectra (XANES) of transition-metal aqueous complex in solution. The metal K edges of Ni2+ and Co2+ are analyzed by multiple-scattering the ory using clusters of different size and different final-state potenti als. On this basis, the effect of hydrogen atoms of the water molecule s on the theoretical XANES spectra has been investigated. The calculat ions show that the intensity ratio and width of the main features of t he spectrum are sensitive to the presence and the geometrical position of hydrogen atoms. A very good agreement between experimental data an d theoretical calculations has been obtained using final-state potenti als built on the basis of the self-consistent field procedure and clus ters with a well-defined geometrical position of hydrogen atoms.