Photographical Record of the Dispersion Surface in Rotating Crystal Electron Diffraction Pattern

Abstract

Strong interacting wave fields in a wedge-shaped crystal are separated into different plane waves when leaving the crystal and reveal points on the dispersion surface. By rotating the crystal while moving the film one obtains a photographical record of a section through the dispersion surface which may be compared with theory. An experiment with a macroscopic MgO wedge is reported. The 002 interference with excitation error nearly zero was recorded near the [I10] zone axis while rotating the crystal about the [001] axis. The diagrams are compared with dynamical 17-beam calculations. The results show that a reduction of the infinite dynamical system of equations to 17 equations is correct under these special geometrical conditions.