Principles & Practice of Electron Diffraction - CIME | EPFL

Nano-area electron diffraction

Image the condenser aperture using a third condenser lens
=> nanometer-sized beam with parallel illumination

Zuo et al. Microscopy Research and Technique 64 347 (2004) 101

Duncan Alexander: Principles & Practice of Electron Diffraction November 2010, EPFL

Nano-area electron diffraction

Method developed for nano-objects where no dynamical scattering problem but phase is required
- therefore need coherent illumination that you do not obtain with CBED

Electron diffraction pattern from single double-walled carbon nanotube
- can determine chirality

Duncan Alexander: Principles & Practice of Electron Diffraction November 2010, EPFL 102

Phase/orientation mapping

NanoMEGAS ASTAR: phase and orientation mapping in TEM
– similar to EBSD in SEM but e.g. much higher spatial resolution (~5 nm possible)

Record diffraction patterns as electron probe moved across sample

Analyse diffraction patterns by “template matching”
– i.e. correlate to ~2000 patterns simulated at different orientations

Combine with precession and can achieve angular resolution of < 1°

Orientation map for nanocrystalline Cu: Phase map showing local martensitic
structure of steel at stacking faults:

Images from NanoMEGAS company literature 103

Duncan Alexander: Principles & Practice of Electron Diffraction November 2010, EPFL

References

“Transmission Electron Microscopy”,Williams & Carter, Plenum Press

“Transmission Electron Microscopy: Physics of Image Formation and
Microanalysis (Springer Series in Optical Sciences)”, Reimer, Springer Publishing

“Electron diffraction in the electron microscope”, J.W. Edington, Macmillan Publishers Ltd

“Large-Angle Convergent-Beam Electron Diffraction Applications to Crystal Defects”, Morniroli,
Taylor & Francis Publishing

http://escher.epfl.ch/eCrystallography

http://www.doitpoms.ac.uk

JEMS Electron Microscopy Software Java version
http://cimewww.epfl.ch/people/stadelmann/jemsWebSite/jems.html

Web-based Electron Microscopy APplication Software (WebEMAPS)
http://emaps.mrl.uiuc.edu/

http://crystals.ethz.ch/icsd - access to crystal structure file database
Can download CIF file and import to JEMS

Duncan Alexander: Principles & Practice of Electron Diffraction November 2010, EPFL 104