Polarization-dependent EXAFS studies on the structures of Mo oxides dispersed on single crystals

Polarization dependent total reflection fluorescence extended X-ray absorpt ion fine structure (PTRF-EXAFS) is reviewed briefly. This technique gives 3 -dimensional information about the local structure around the X-ray absorbi ng atom even if the atom is highly-dispersed on the surface. We have applie d the technique to the Mo oxide species dispersed on single crystal oxide s urfaces, such as Al2O3(0001), MgO(100) and TiO2(110). Tetrahedral Mo specie s is found on MgO(100) surface while tetragonal pyramid species and octahed ral dimer Mo species are found on Al2O3 and TiO2 surfaces, respectively. Th e structure dependences on support can be explained by the acidity and basi city of the support oxides. (C) 2001 Elsevier Science B.V. All rights reser ved.