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MM: Fachverband Metall- und Materialphysik

MM 14: Topical Session Nanoanalytics using Small-Angle Scattering II

MM 14.3: Vortrag

Dienstag, 24. März 2009, 12:30–12:45, IFW A

Investigation of multiphase systems by small-angle scattering — •Dragomir Tatchev — Helmholtz Zentrum Berlin, Glienicker Str. 100, 14109 Berlin, Germany and Institute of Physical Chemistry - Bulgarian Academy of Sciences, Acad. G.Bonchev Str., Bl. 11, 1113 Sofia, Bulgaria

The two-phase approximation in small-angle scattering is well known and still dominating the data analysis. The intensity scattered at small angles is proportional to the second power of the difference between the scattering densities of the two phases. Simultaneously, scattering contrast variation techniques are widely used and they obviously target multiphase systems or systems with gradually varying scattering density since if no parasitic scattering contributions are present the scattering contrast variation would only change a proportionality coefficient. However, there are only scarce attempts to generalise the SAS theory for multiphase systems. Here we show that the scattered intensity at small-angles of a multiphase system can be presented as a sum of scattering of two-phase systems and terms describing interference between all pairs of phases. Extracting two-phase scattering patterns, called phase scattering functions, from multiphase samples by contrast variation is possible. These two-phase patterns can be treated with the usual SAS formalism. In the case of anomalous SAXS, the phase scattering functions have significant advantage over the partial structure factors since the later depend on all phases in the sample. The case of gradually varying scattering density is also discussed.