Orientation Dependence ofK-Absorption Extended Fine Structure of a Single Crystal of Germanium

The fine structure of the $K$-absorption spectrum of a Ge single crystal was investigated with 90% polarized radiation. A single-crystal spectrometer and a fine focus x-ray tube were used. Absorption curves were obtained up to 300 eV from the main edge for five different positions of the absorber. No shifts of the extrema of the fine structure were observed. This experimental result is in agreement with theoretical considerations given here which show that absorption is independent of orientation for cubic symmetry and also for other cases of symmetry.