electron microscopy



Analytical Electron Microscopy (AEM)

Utilized signals: inelastically scattered electrons (energy-loss electrons) and X-rays


Methods Information
EDXS qualitative and quantitative element analysis
EELS qualitative and quantitative element analysis. Bonding situation (energy-loss near-edge structure ELNES), coordination and interatomic distances (extended energy-loss fine structure EXELFS)
ESI element distribution
STEM + EDXS/EELS element distribution


Comparison of EELS and EDXS

high detection efficiency for low Z elements
high detection efficiency for high Z elements
elemental, chemical and dielectric information
elemental information only
excellent energy resolution (0.3-2 eV) results in few peak overlaps; fine structures of the ionization edges can be analyzed (ELNES, EXELFS)
low energy resolution (> 100 eV) causes frequent overlaps
very efficient and high sensitivity to most elements => fast and efficient mapping technique
inefficient signal collection and detection
=> X-ray mapping is time-consuming
fast technique; complex processing required
slow technique; only simple data processing required


Restrictions: Since electron-matter interactions are mostly elastic, high electron doses are necessary for all methods of analytical electron microscopy. A long recording time may be required for a good signal/noise ratio which is only possible if the sample is stable under the intense electron beam and if no specimen drift occurs.
Since ionization edges occur at characteristic energies and have different shapes, not all methods are equally suitable for all elements

ETH Zürich | ETH chemistry department | ETH inorganic chemistry

modified: 6 February, 2015 by F. Krumeich | © ETH Zürich and the authors