Improved extended-x-ray-absorption fine-structure (EXAFS) studies applied to the investigation of Cu-O, Cu-N, and Cu-Br bond lengths

Extended-x-ray-absorption fine-structure spectra in the region of the Cu K edge are presented for Cu, CuO, Cu₂O, CuSO₄, CuSO₄·{}5H₂O, Cu(OH)₂, Cu(NO₃)·{}3H₂O, [Cu(NH₃)₄]²⁺, and CuBr₂. By the usual Fourier-analysis method, bond lengths for Cu-O, Cu-N, and Cu-Br are determined. Further, a back-transformation into real space is used which allows us to check the consistency of the evaluation for the whole energy range investigated. The advantages of this evaluation are: bond lengths can be taken from regions of high accuracy of the experimental data, the k dependence of the phase shifts can be checked and this presentation gives a criterion on how to fit the reference energy necessary for the energy-momentum conversion. The bond lengths determined with this method agree to within 0.02 {}A with reliable x-ray diffraction data.