Extended x-ray absorption fine structure (EXAFS) measurements were performed for concentrated aqueous rare earth perchlorate solutions (R=28; R is the moles of water per mole of salt) in the liquid state at room temperature and in the glassy state at liquid nitrogen temperature. The quantitative analysis of the EXAFS data has revealed that the hydration number changes from about nine for light rare earth ions to about eight for heavy rare earth ions through the intermediate ions of Sm3+ ∼Eu3+ in both liquid and glassy states. The average Ln3+ –OH2 distances were determined and they are in agreement with previously reported values from x-ray and neutron diffraction. The Debye–Waller factor of the average Ln3+ –OH2 bonds for the light rare earth ions was larger than that for the heavy ions, suggesting that the hydration shell of the light rare earth ions is statically disordered, consisting of different Ln3+ –OH2 bonds.
Electronic and structural dynamics of an industrially relevant Pt/CeO2–ZrO2 catalyst with an ordered arrangement of Ce and Zr ions during oxygen storage/release processes at 573–773 K were studied in real time by time‐resolved energy‐dispersive XAFS at the Zr K edge and Ce L3 edge (see experimental setup). On the basis of these results, the roles of Ce and Zr ions in the function of the mixed‐oxide catalyst were elucidated.
Three-dimensional analysis of structures for dispersed Cu species on a TiO 2 (110) surface has been performed by a polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) technique. The dispersed Cu species were prepared by a chemical reaction between Cu(DPM) 2 and a TiO 2 (110) surface and reduced with H 2 . The Cu(DPM) 2 dissociatively adsorbed on the 2-fold site of bridging oxygen atoms of the TiO 2 (110) surface to form a Cu(DPM)(O-) 2 species. Subsequent reduction of the Cu species with H 2 at 363 K produced Cu 3 trimers that were bound to the bridging oxygen atoms with the trimer plane inclined at about 30°from the TiO 2 (110) normal. There were direct Cu-O bonds at the Cu 3 trimer/TiO 2 (110) interface in addition to Cu-Cu bonds. Further reduction at 473 K produced three-dimensional prismatic small Cu 6 clusters by vertical growth in the [110] direction of the Cu fcc lattice. Orientations of the Cu 3 triangle and Cu 6 prism clusters may be regulated by the interaction between the Cu atoms and the bridging oxygen atoms on the anisotropic TiO 2 (110) surface.
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