Atomic EXAFS: evidence for photoelectron backscattering by interstitial charge densities

We present further evidence for backscattering of photoelectrons at interst itial charge densities. Two low-Z adsorbate-metal systems, namely (2x3)N/Cu (110) and (root 2X2 root 2)R45 degrees O/Cu(100), show clear evidence of at omic EXAFS. Directional bonding which is a characteristic of these two reco nstructed systems is most likely to be the reason for the strong AXAFS foun d in the experimental data. Moreover, it turns out that low-Z adsorbates ar e ideal candidates to study such a phenomenon as multielectron excitations do not interfere with the AXAFS oscillations. (C) 1999 Elsevier Science B.V . All rights reserved.