AN X-RAY-ABSORPTION STUDY OF GOLD COORDINATION-COMPOUNDS - EXAFS REFINEMENTS AND DOUBLE-ELECTRON EXCITATION BACKGROUND

X-ray absorption spectra at the Au L edges of Au(PPh3)Cl, Au(PPh3)2Cl and KAuCl4.2H2O have been collected as a function of temperature. Data analysis of the extended x-ray absorption fine structure was carried out with the GNXAS package performing an appropriate treatment of the multiple-scattering effects involving several ligand atoms. The accura cy of the current analysis procedures for the Au L edges is assessed a nd the sensitivity to coordination numbers and distances is establishe d. Evidence for the presence of a [2p4f] double-electron excitation in the atomic Au background is obtained for the first time. The results presented in this paper are of general importance for improving data a nalysis at the Au L edges and in particular for improving the EXAFS re sults in Au cluster compounds.