electron microscopy
 

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Energy-Filtered Transmission Electron Microscopy (EFTEM)

Energy filtering is a valuable tool for materials characterization. It can be applied for various problems:
1. Zero-loss filtering
By using only the zero-loss beam, all inelastically scattered electron are omitted (reduction of noise). That leads to increased contrast in TEM images (important for specimens with low contrast, e.g. biological specimens) or in diffraction patterns.
2. Electron spectroscopic imaging

By using electrons with a well-defined energy loss (ionization edge), elemental distribution maps can be generated.

 

The GIF (Gatan Imaging Filter) is mounted below the column of a TEM. It consists of two main parts:
1. Magnetic prism
In the curved magnetic field, electrons with different energies are dispersed, and consequently an EEL spectrum is obtained at the end of this part. In fact, the magnetic prism is the same as in a parallel electron energy loss spectrometer, and, of course, an EEL spectrum can be measured with the GIF as well.
2. Optical column
An energy range is selected by a slit located at the dispersion plane. In imaging mode, electrons of the selected energy pass through the lenses of the optical system, and an energy-filtered image occurs at the end of the GIF, where a slow-scan CCD camera is installed for image recording.

Further information about EFTEM can be found at the FELMI page (TU Graz).

Generation of X-rays

   
ETH Zürich | ETH chemistry department | ETH inorganic chemistry

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