INFLUENCE OF DOUBLE-ELECTRON TRANSITIONS ON THE EXAFS L EDGES OF RARE-EARTH SYSTEMS

This work presents an x-ray-absorption study at the L edges of several rare-earth compounds. In both L1-edge and L3-edge spectra, anomalous features are clearly detected in the EXAFS region and have been associ ated with the creation of 2s4d and 2p4d double-core hole states, respe ctively. Comparison of theoretical calculations with the experiments a re carried out using the results of explicit computation of cross sect ions for the allowed mainline (L edge) and double-electron (LN4,5 edge s) which identify the transitions expected to be observable. In additi on, the excitation energies of all of these allowed transitions are gi ven. The influence of multielectron transitions on the EXAFS data anal ysis is discussed for several rare-earth-based systems. An estimate of the error introduced by neglecting the presence of double-electron tr ansitions on coordination numbers and bond distances is given, based o n these experimental data.