Pendellösung Measurement of the Atomic Scattering Factor of Germanium

The atomic scattering factor of the (111) and (220) reflections of germanium were determined by two independent dynamical measurements: (a) from the absolute integrated intensities of Bragg reflections, and (b) from a determination of the Pendellösung period. The Pendellösung measurements show that for a relatively highly absorbing material such as germanium the scattering factor can be determined to about ±1% only for the low-order reflections. The resulting scattering factors from the two types of measurements disagree sufficiently outside of experimental uncertainty to conclude that the difference is real. Dynamical theory in its present state offers no explanation why the results should be different.