Small-angle neutron- (SANS) and X-ray-scattering (SAXS) patterns obtained at 40 °C from 0.0729 m D2O solution of cesium dodecyl sulfate (CsDDS) have been simultaneously evaluated in terms of the conventional two-shell model, a three-shell model created for demonstration purposes, and a newly developed - and partly tested - four-component model. The simultaneous fitting is based on the fact that the two types of coherent scattering patterns differ only in the neutron- and X-ray scattering lengths. For comparison, the SANS and SAXS patterns were evaluated separately, too. In contrast to the two- and three-shell models, the four-component model is able to represent the continuously varying spatial distribution of the scattering contrast. From the results, it seems that the most reliable data are obtained from fitting the four-component model simultaneously to both patterns. Along with (approximate) core- and counterion profiles, application of the latter model can result in the spatial distribution of the solvent molecules around the micellar center. If an atom or a molecular group has well-distinguishable scattering contrast relative to both types of scattering (such as Cs+ counter-, and -SO4- - headgroup-ions), utilization of the four-component model enables their molecular volumes to be treated as variable model parameters, thus providing a unique method for determining their hydration properties in a structured nonsimple liquid.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry