Energy filtered photoemission electron microscopy (PEEM) is realized using different more or less complex methods. Techniques in use are retarding field analyzers, time of flight spectrometers and energy dispersive band pass analyzers.
The most powerful technology for energy resolved imaging with PEEM is band-pass imaging with the NanoESCA instrument using a double hemispherical analyzer /1/.
This contribution compares two other versatile approaches that are high pass energy filtering /2/ and time of flight imaging /3/.
We show recent results with a state of the art high pass imaging energy filter (IEF). With this technique we achieved an energy resolution of about 75 meV and a lateral resolution of better than 30nm.
With a delay line detector (DLD) we realized time of flight PEEM with a time resolution of 300 psec and a corresponding energy resolution of about 50meV. With this technique we visualized the energy and time dispersion of "hot spots" excited by two photon photo emission (2PPE). We acquired a series of time slice images of a micro structured Ag:Si sample excited by a 400nm pulsed diode laser. The "hot spots" show a lower cut off energy compared to all other sample regions. We derived TOF spectra integrated over 3x109 laser pulses. Each spectrum corresponds to a certain area at the sample. Huge intensity differences between "hot spots" and background areas demonstrate the good dynamics range of the DLD.
The advantages and limitations of the two approaches are compared and discussed. A combination of the IEF and the DLD techniques opens possibilities for experiments, where both low and high intensity measurements are needed.
/1/ M.Escher et al., J.Phys.:Cond. Matt. 17 (2005), 1329-1338
/2/ M.Merkel et al., Surf.Sci. 480 (2001), 196-202
/3/ A.Oelsner et al., Rev.Sci.Instr. 72, 10 (2001), 3968-3974
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