Acta Crystallographica Section A

Foundations of Crystallography

Volume 69, Part 4 (July 2013)

research papers

Acta Cryst. (2013). A69, 427-434    [ doi:10.1107/S0108767313010143 ]

Digital electron diffraction - seeing the whole picture

R. Beanland, P. J. Thomas, D. I. Woodward, P. A. Thomas and R. A. Roemer

Abstract: The advantages of convergent-beam electron diffraction for symmetry determination at the scale of a few nm are well known. In practice, the approach is often limited due to the restriction on the angular range of the electron beam imposed by the small Bragg angle for high-energy electron diffraction, i.e. a large convergence angle of the incident beam results in overlapping information in the diffraction pattern. Techniques have been generally available since the 1980s which overcome this restriction for individual diffracted beams, by making a compromise between illuminated area and beam convergence. Here a simple technique is described which overcomes all of these problems using computer control, giving electron diffraction data over a large angular range for many diffracted beams from the volume given by a focused electron beam (typically a few nm or less). The increase in the amount of information significantly improves the ease of interpretation and widens the applicability of the technique, particularly for thin materials or those with larger lattice parameters.

Keywords: electron diffraction; symmetry determination; CBED; LACBED; computer control.

aviplay filedownload file

AVI file (1218.3 kbytes)
[ doi:10.1107/S0108767313010143/td5013sup2.avi ]
Uncorrected.avi - beam position while beam is tilted with no compensation

aviplay filedownload file

AVI file (1224.9 kbytes)
[ doi:10.1107/S0108767313010143/td5013sup3.avi ]
Corrected.avi - beam position with compensation


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