Extended X-Ray Characteristic Fluorescence Fine Structure above the K-Edge of Ni and NiO by Fast Electron Excitation

Abstract
The extended X-ray fluorescence fine structure (EXFLUFS) above the Ni K-edge in Ni and NiO in the appearance potential regime by fast electron excitation was measured by means of scanning electron microscope with Si (Li), crystall detector and rnulticanal analyzer in the raster or single mode. The conventional EXAFS-type analysis including the tables of plane-wave EXAFS phases and amplitudes of Teo & Lee and/or tables of curved-wave EXAFS phases of McKale et al. was made in order to obtain the structural information. The Fourier filtered peak fitting with the phase shift correction from Teo & Lee gives interatomic distances, which agree well with cristallographic and EXAFS data. The fitting resultas of experimental data suggest that conventional EXAFS phase shift correction can be safety used for EXFLUFS analysis with a little correction, if needed. The intensities of EXFLUFS peaks differ from those of EXAFS case, probably because of non-dipole excitation, as well as the elastic scattering of primary electron before and after the inelastic scattering event. The EXFLUFS method is a bulk sensitive method which insures several order higher spatial resolution than in the synchrotron case, as well as it allows the deep core excitation in a wide energy range.