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 $\mathrm{Cu} K$ edge are presented for Cu, CuO, ${\mathrm{Cu}}_2$O, CuS${\mathrm{O}}_4$, CuS${\mathrm{O}}_4$·5${\mathrm{H}}_2$O, Cu${\mathrm{}\left(\mathrm{OH}\right)\mathrm{}}_2$, Cu(N${\mathrm{O}}_3$)·3${\mathrm{H}}_2$O, ${\left[\mathrm{C}\mathrm{u}{\left(\mathrm{N}{\mathrm{H}}_3\right)}_4\right]}^{2+}$, and Cu${\mathrm{Br}}_2$. 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 ÅA with reliable x-ray diffraction data.