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

Abstract

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${\mathrm{O}}_{4}$\ifmmode\cdot\else\textperiodcentered\fi{}5${\mathrm{H}}_{2}$O, Cu${(\mathrm{OH})}_{2}$, Cu(N${\mathrm{O}}_{3}$)\ifmmode\cdot\else\textperiodcentered\fi{}3${\mathrm{H}}_{2}$O, ${[\mathrm{C}\mathrm{u}{(\mathrm{N}{\mathrm{H}}_{3})}_{4}]}^{2+}$, 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 \AA{}A with reliable x-ray diffraction data.