The local structure and electronic state based on conventional XAFS ( X-ray absorption fine structure ) are the average among several sites in sample. Another problem of XAFS is the difficulty to measure the absorption edge for trace amounts of element in the presence of a high concentration of heavy element(s) ( strong absorber/fluorescence emitter ). Herein, XAFS combined with a fluorescence spectrometer was applied to site-selective observation of Cu0 and CuI sites for Cu/ZnO catalysts by utilizing the chemical shift of each site and to a trace amount of lead adsorbed from a low concentration of aqueous Pb2+ solution.
By the improvements of Johansson-type Ge(111) crystal and the control of two slits position located between sample and crystal and between crystal and detector, the energy resolution of the spectrometer was decreased to 1.1 eV. Thereby, site selection of Cu0 and CuI sites was improved and metallic Cu site and atomically-dispersed CuI site over ZnO surface were observed, respectively. The improvements of spectrometer also increased the photon counts at detector. XANES spectrum of 0.12 wt% of Pb2+on Mg6Fe2(OH)16(CO3)•3H2O ( 1, Fe content 17.35 wt% ) was successfully obtained. Major part of Pb2+exchanged with surface hydroxyl groups of (1).