Editing Ewald's sphere (section)

{{Short description|Energy conservation during diffraction by atoms}}
The '''Ewald sphere''' is a geometric construction used in [[electron diffraction|electron]], [[neutron diffraction|neutron]], and [[X-ray crystallography|x-ray]] diffraction which shows the relationship between: 
* the [[wavevector]] of the incident and diffracted beams, 
* the [[Bragg angle|diffraction angle]] for a given reflection, 
* the [[reciprocal lattice]] of the [[crystal]].

It was conceived by [[Paul Peter Ewald]], a German physicist and crystallographer.<ref>{{cite journal |title=Die Berechnung optischer und elektrostatischer Gitterpotentiale |lang=de |year=1921 |author=Ewald, P. P. |journal=Annalen der Physik |volume=369 |issue=3 |pages=253–287 |bibcode=1921AnP...369..253E |doi=10.1002/andp.19213690304 |url=https://zenodo.org/record/1424363}}</ref> Ewald himself spoke of the '''sphere of reflection'''.<ref>{{cite journal |doi=10.1107/S0567739469000155 |title=Introduction to the dynamical theory of X-ray diffraction |year=1969 |author=Ewald, P. P. |journal=Acta Crystallographica Section A |volume=25 |issue=1 |pages=103–108 |bibcode = 1969AcCrA..25..103E |doi-access=free}}</ref> It is often simplified to the two-dimensional "Ewald's circle" model or may be referred to as the Ewald sphere.