The Ewald sphere for high energy electrons has a large radius (because l
is so small) and therefore it samples a virtually plane
section of the reciprocal lattice, often the zero order
Laue zone. Because of relrod streaking there are usually
many spots in the recorded diffraction pattern. Electron
diffraction patterns can be equated with reciprocal lattice
patterns.
Indexing
| It is often possible to
index an electron diffraction
pattern by noting its symmetry. A reciprocal lattice
has the same symmetry as its real lattice.
 This
simulation shows a 2-D representation of a large radius Ewald sphere
intersecting a reciprocal lattice. Try to identify the zero order and first order
diffraction spots.
|
|
If insufficient obvious symmetry is present it may be necessary to use the ratio
technique described in the next section.
Why are streaking effects
more important for electron diffraction than for x-ray diffraction?
