Geometrical Relationship Between Kikucki Line Position and Excitation Error in Electron Diffraction

摘要

All of the main features of the geometry of Kikuchi lines can be thoroughly explained using the treatment first proposed by Kikuchi in which the observed diffraction lines are considered to arise from the elastic (Bragg) scattering of electrons that had been previously scattered inelastically by the specimen. The positions of the lines occur at the intersection of Kikuchi cones or Kossel cones with the Ewald sphere, giving an accurate indication of the orientation of the specimen relative to the incident beam direction, and providing a rapid means (inspection) of deducing the sign of the deviation parameter, s. Less obvious from these traditional presentations however is the actual magnitude of s. This paper presents an alternative geometrical construction employing multiple Ewald spheres to illustrate the phenomenon of multiple scattering which is responsible for the formation of Kikuchi lines, and to provide a straightforward derivation of the excitation error from the relative positions of the Kikuchi lines and their corresponding diffraction spots. (ERA citation 11:038739)