Structure Refinement by Taking Dynamical Diffraction into Account

5. Conclusion

It is possible to determine structures from dynamic electron diffraction data. In most cases low R-values are obtained, which are comparable to those of X-ray single crystal diffraction data. The presence of strong dynamic scattering makes the structure refinement more complex and certainly more time consuming. As such it is a disadvantage. However, it also has a large advantage, because the scattering of a column of atoms depends not only on the scattering potential of the atoms but also on the thickness, resulting in an oscillation in the scattering potential of the column with thickness. Thus for certain thicknesses a column containing only weakly scattering atoms show a higher scattering than a column containing strongly scattering atoms. Consequently by using various thicknesses the weakly scattering atoms can be determined with a higher accuracy. Furthermore it can be used to discriminate between atom types as has been done in the refinement of Ce₅Cu₁₉P₁₂, which was started with a model with only Cu atoms on all sites, where by refining the occupancies the locations of the Ce and P atoms were determined.