Site-selective XAFS spectroscopy tuned to surface active sites of copper catalysts

To overcome the problem of X-ray absorption fine structure (XAFS) spectrosc opy in which the obtained information is the average for all sites in sampl e, Rowland-type fluorescence spectrometer was designed to measure site-sele ctive XAFS spectra by utilizing the chemical shift of emission peak for eac h site. Johansson-type cylindrically-bent Ge(111) crystal and scintillation counter were mounted on the spectrometer. The improvement of energy resolu tion of spectrometer was discussed when the primary beam size and two slit size in the Rowland circle were varied. The energy resolution was similar t o1.1 eV, smaller than the core-hole lifetime width for Cu K alpha (1) (2.11 eV). The site selection of the Cu-0 and Cu-1 site-tune spectra was experim entally measured for the physical mixture of Cu metal+Cul and for Cu/ZnO ca talyst. Obtained experimental site selection was compared to the theoretica l estimations. (C) 2001 Elsevier Science B.V. All rights reserved.