Application of new synchrotron powder diffraction techniques to anomalous scattering from glasses

摘要

The authors have applied two synchrotron powder diffraction techniques to the measurement of high quality anomalous scattering diffraction data for amorphous materials. One of these methods, which uses a curved perfect crystal analyzer to simultaneously diffract multiple powder lines into a position sensitive detector, has been shown to possess high resolution, low background and very high counting rates. This data measurement technique provides excellent energy resolution while minimizing systematic errors resulting from detector non-linearity. Anomalous scattering data for a cesium germanate glass collected using this technique will be presented. The second powder diffraction technique uses a flat analyzer crystal to deflect multiple diffraction lines out of the equatorial plane. Calculations show that this method possesses sufficient energy resolution for anomalous scattering experiments when a perfect crystal analyzer is used and is experimentally much simpler. Future studies will make use of a rapid sample changer allowing the scattering from the sample and a standard material (a material not containing the anomalous scatterer) to be measured alternately at each angle, reducing systematic errors due to beam instability or sample misalignment.