EXTENDED X-RAY CHARACTERISTIC FLUORESCENCE FINE-STRUCTURE ABOVE THE K-EDGE OF NI AND NIO BY FAST-ELECTRON EXCITATION

The extended X-ray fluorescence fine structure (EXFLUFS) above the Ni K-edge in Ni and NiO in the appearance potential regime by fast electr on excitation was measured by means of scanning electron microscope wi th Si (Li) crystal detector and multicanal analyzer in the raster or s ingle mode. The conventional EXAFS-type analysis including the tables of plane-wave EXAFS phases and amplitudes of Teo & Lee and/or tables o f curved-wave EXAFS phases of McKale et al. was made in order to obtai n the structural information. The Fourier filtered peak fitting with t he phase shift correction from Teo & Let gives interatomic distances, which agree well with crystallographic and EXAFS data. The fitting res ults of experimental data suggest that conventional EXAFS phase shift correction can be safely used for EXFLUFS analysis with a little corre ction, if needed. The intensities of EXFLUFS peaks differ from those o f EXAFS case, probably because of nondipole 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 synchroto n case, as wed as it allows the deep core excitation in a wide energy range.