Extended fine Auger structure spectroscopy of Ag and Cu

The extended fine Auger structure (EXFAS) spectra of Ag(111) and polycrystalline Cu have been recorded by use of both angle-resolved and angle-integrated electron spectrometers. Extended fine Auger structure associated with both the Ag N23 and Ag M45 core-hole states is observed. The temperature variation (between 150 and 600 K) of both Ag extended fine-structure spectra is reported. The Cu M23ɛV EXFAS of polycrystalline Cu is compared to the Cu M23 electron-energy-loss fine structure and to calculated Cu L2 extended x-ray-absorption fine structure (EXAFS). The angle-integrated results are interpreted in terms of an EXAFS-like origin of the extended fine Auger structure, although strong contributions from various diffraction processes may also be contributing. The extended fine Auger structure is found to depend on the extent of angular integration used in the data collection. This is tentatively explained in terms of changes in the relative contributions of EXAFS-like and diffraction mechanisms. Further experimental tests of the origin of this signal are proposed.