Multiple-wavelength anomalous dispersion techniques applied to powder data: a probabilistic method for finding the substructure via joint probability distribution functions

A new joint probability distribution function method is described to find theanomalous scatterer substructure from powder data. The method requires twowavelengths; the conclusive formulas provide estimates of the substructurestructure factor moduli, from which the anomalous scatterer positions can befound by Patterson or direct methods. The theory has been preliminarily appliedto two compounds, the first having Pt and the second having Fe as anomalousscatterer. Both substructures were correctly identified.