Ewald's_sphere
Ewald's sphere
Energy conservation during diffraction by atoms
The Ewald sphere is a geometric construction used in electron, neutron, and x-ray diffraction which shows the relationship between:
- the wavevector of the incident and diffracted beams,
- the diffraction angle for a given reflection,
- the reciprocal lattice of the crystal.
It was conceived by Paul Peter Ewald, a German physicist and crystallographer.[1] Ewald himself spoke of the sphere of reflection.[2] It is often simplified to the two-dimensional "Ewald's circle" model or may be referred to as the Ewald sphere.