R. Serimaa et al., AN IMPROVED REGULARIZATION TECHNIQUE FOR ANALYSIS OF ANOMALOUS X-RAY-SCATTERING DATA - PLATINUM URIDINE BLUE SULFATE AS AN EXAMPLE, Journal of applied crystallography, 29, 1996, pp. 390-402
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.