Berlin 2015 – scientific programme

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MI: Fachverband Mikrosonden

MI 10: Poster: Microanalysis and Microscopy

MI 10.7: Poster

Wednesday, March 18, 2015, 15:00–17:30, Poster B

Chaotic behavior in ASAXS formalisms — •Sören Gayer, Ulla Vainio, and Andreas Schreyer — Helmholtz-Zentrum Geesthacht, Germany

Structures of low scattering length density contrast are inaccessible for small-angle x-ray scattering (SAXS) measurements, even if the different phases are composed of different elements. Fortunately, resonant absorption athe the absorption edges leads to a large dispersion correction of the scattering length of the resonant atoms. This anomalous scattering process can be used to increase the previously low contrast by a variation of the photon energies.

There exist a number of methods to solve the set of equations obtained by these anomalous SAXS (ASAXS) measurements at several photon energies. To test the behavior of three different methods in the presence of systematic measurement errors, numerical simulations of ASAXS signals of different structures were performed.

These simulations revealed threshold uncertainties in the absolute intensity scale for which the solutions, especially of the partial structure factor and Stuhrmann method, show chaotic behavior.