AN IMPROVED REGULARIZATION TECHNIQUE FOR ANALYSIS OF ANOMALOUS X-RAY-SCATTERING DATA - PLATINUM URIDINE BLUE SULFATE AS AN EXAMPLE

A new iterative way to apply the Tikhonov regularization method for so lving partial structure factors from anomalous X-ray scattering data i s presented. It is used to obtain the regularized Pt-Pt partial struct ure factor in a complex amorphous material, platinum uridine blue, con taining many atomic species, utilizing experimental anomalous wide-ang le X-ray scattering data. Since only platinum has a suitable absorptio n edge for the measurement, the problem is very much ill-posed, and wi thout regularization only unreliable solutions are obtained. The avera ge Pt-Pt distances, determined from the Pt-Pt partial distribution fun ction, are 3.0 and 5.7 Angstrom and the coordination number at 3.0 Ang strom is about 1. Accordingly, the dominating Pt-structures of Pt-urid ine blue are dinuclear. The success of this method indicates that we m ay use anomalous scattering to obtain important, detailed information about the structure of very complex amorphous materials.