The incorporation of energy filtering into the FOCUS PEEM or FOCUS IS-PEEM yields improved performance and opens up new application possibilities. The imaging energy filter acts as a high pass filter for the full image; it is not visible in the image under normal operating conditions. The retarding field energy filter is situated in front of the multichannelplate, and can be easily retrofitted to existing PEEMs.
Using laboratory excitation sources (threshold photoemission microscopy), imaging at specific work functions with energy filtering yields a strongly enhanced contrast. Setting the energy filter to a specific electron energy facilitates element-specific mapping (using difference images at XPS or AES lines) with increased contrast. The energy filter effectively reduces chromatic aberrations, i.e. the energy spread of the electrons contributing to the formation of the image, yielding improved spatial resolution in synchrotron applications (chemical and magnetic imaging).
The energy filter can also be used for microspectroscopy analysis - XPS, UPS and AES spectra up to a kinetic energy of 1500 eV and with energy resolution well below 1 eV can be obtained in areas smaller than 1 µm, as selected by the iris aperture.
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