Anomalous wide angle X-ray scattering (AWAXS) and heterogeneous catalysts Original Research Article

This review paper will be focused on anomalous wide angle X-ray scattering (AWAXS) and more precisely on the numerous breakthroughs, which have been achieved using this technique in heterogeneous catalysis. We present some basic elements of classical X-ray diffraction (XRD) and underline the limitation of this technique when we consider the structural characterisation of nanometer scale metallic clusters supported on supports such silica, zeolite or γ-alumina. Then we introduce the theoretical formalism of the anomalous diffraction and more precisely the f′ and f″ dispersive terms, including other physical processes such Compton scattering and fluorescence. A brief presentation of experimental set-ups dedicated to anomalous scattering implemented on different synchrotron radiation centres is given. We conclude with a review of the different studies already published and with some selected examples related to nanometer scale mono and bimetallic, sulfide and oxide clusters to illustrate the nature of information obtained through this technique and discuss the advantages and the limits of this approach.