OBTAINING RELIABLE STRUCTURAL PARAMETERS FROM EXAFS

The accuracy of the structural parameters (i.e. type of neighbour, num ber of neighbours of a specific type, distance between absorber and ne ighbour, and disorder) that are obtained from the analysis of EXAFS sp ectra is in theory only depending on the errors in the data. However, the experimental set-up, the standard used to build the model EXAFS, a nd data analysis method may introduce systematic errors. This paper di scusses several methods to decrease the errors associated with the met hod of data analysis. With MoS2 as an example the use of phase correct ed Fourier transforms to determine the type of neighbour is demonstrat ed. The conventionally applied k(3)-weighting of the data was compared to k(1)-weighting and weighting by the inverse of the statistical err or in the refinement of the structural parameters of PtO2. Weighting t he data with the inverse of the statistical error gives results in agr eement with XRD structure determinations and the best goodness of fit values (epsilon(v)(2)). (C) 1998 Elsevier Science B.V.