New insight on the local structure of Cu2+ion in the solution of CuBr2by EXAFS studies

CuBr2 solutions at different concentrations were studied by extended X-ray absorption fine structure (EXAFS) at the Cu K edge. In the saturated solution Cu2+ ions have chemical bonds with 3.0 oxygen atoms and 0.9 Br ion at about 1.96 Å and 2.42 Å, respectively. It indicates that the CuBr4-2 configuration exists with a ratio of 25% under this condition. In the dilute solutions no evidence of Br ions contributions in the first shell around Cu2+ ions occurs. The almost identical X-ray absorption near edge structure (XANES) and EXAFS characters address similar local environments around Cu2+ in agreement with results of the EXAFS fit taking into account only the contributions of Cu-O bonds.