We report on a laboratory EXAFS spectrometer optimized for transmission dispersive mode. Absorption edges ranging from 6 to 20keV can be studied. Factors determining energy range and resolution are detailed. A new asymmetric geometry which allows to use all the lattice planes of the dispersing crystal is described and the choice of the best plane analysed. EXAFS spectra of Cu metal and Cu acetate, obtained on this laboratory facility, are compared to the corresponding spectra recorded on the French synchrotron facility (LURE).
The computational procedure, based on Warren's exact method for an amorphous sample with more than one atom, was developed to obtain the short-range order structural parameters from the differential anomalous X-ray scattering data, collected using the synchrotron radiation. The experimental differential radial distribution functions were fitted with the true distribution functions expressed in an analytical form and broadened by convolution with the pair functions. It was found that atoms in the amorphous Cd-As films remain almost tetrahedrally coordinated and the investigated alloys are chemically ordered.
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