Figure 1
(a) The geometry of large-angle convergent-beam electron diffraction (LACBED) for one diffracted beam, ignoring all other diffracted beams. The Bragg condition is satisfied when the incident and exit beams make an angle to the diffracted planes, defining a cone. This gives a parabola on the diffraction pattern which, because of the very small Bragg angle, appears as a straight line in an LACBED pattern (b), taken from a [100] silicon crystal. (c) The corresponding CBED pattern, with a small part of the LACBED pattern visible in the disc. |