DIFFERENTIAL ANOMALOUS SCATTERING STUDY OF PROBE MOLECULES

Over the last several years, anomalous wide angle X-ray scattering (AWAXS) has been developed for the study of disordered solid materials like amorphous metallic, chalcogenides or isolating glasses. AWAXS is a contrast variation method, based on differential analysis of diffraction spectra recorded near and away from the absorption edge of each component in the studied material. This technique is useful in solids for exploring the medium range order over 4 Å and may be considered as an extension of XAFS. AWAXS may give useful information on the pairs correlation functions in liquids, where the brownian motion limits the data extracted from XAFS. Up to now, X-ray diffraction is poorly extended to liquid. The main difficulty remains in the choice of an appropriate sample holder. For non absorbing liquid like molecules diluted in solvent, we combined reflective and transmittive geometry by using a cylindrical cell where the incident and reflected beam are always perpendicular to the window, reducing the absorption due to the window to its minimum. The ability of this cell for diffraction on liquid has been tested at the bromine K-edge on bromoethane BE solubilized in aqueous micellar solution of sodium dodecylsufate SDS. A complete data treatment up to differential structure factor has been achieved and compared to the previous known features of that liquid system.