APPLICATIONS OF ENERGY DISPERSIVE DIFFRACTION WITH SYNCHROTRON RADIATION. P. Suortti, V. Honkimäki, European Synchrotron Radiation Facility, B. P. 220, F-38043 Grenoble Cedex, France

The spectral brightness of a high-field wiggler at the ESRF has been determined by using energy dispersive diffraction (EDD) from well-characterized powder specimens. The results are in a close agreement with the brightness calculated from the emittance of the electron beam and the measured magnetic field of the wiggler. The precisely known brightness of the synchrotron beam can be used in many different studies with EDD. In the case of powder diffraction all reflections up to very high orders are recorded simultaneously, and thermal motion parameters are obtained with high accuracy from the integrated intensities. A new method for resolving the powder pattern was developed. Bragg reflections and the background of smoothly varying inelastic scattering and modulated thermal diffuse and disorder scattering are described by a unified and self-consistent model, which is fitted to the observed diffraction pattern. When two samples of different thicknesses are used in transmission geometry the total attenuation coefficient is obtained over a wide energy range. In the case of a single crystal reflection from one set of Bragg planes are recorded simultaneously. The integrated reflectivities are measured on an absolute scale, and this provides a rapid method for determination of the effects of extinction. The energies where the reflections occur are changed by changing the scattering angle, so that the predictions of extinction theories are tested in short order. Results of these applications are presented.