Author Topic: Duane-Hunt limit  (Read 4433 times)

Nicholas Ritchie

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Re: Duane-Hunt limit
« Reply #30 on: February 12, 2024, 06:08:23 PM »
We know from electron energy loss spectroscopy (EELS) that the electron source is essentially monochromatic from the perspective of X-ray analysis.  Today, monochromated cold field emission beams are used which can produce beams with milli-eV energy spreads.  However, early EELS was performed with thermal sources which had resolutions on the order of 1 eV.  This is the number we should compare to.

Do you have any literature references for the thermal sources that you can share with us?

K. Kimoto, G. Kothleitner, W. Grogger, Y. Matsui, F. Hofer Micron, 36 (2005), p. 185

The bandgap is one of the principal properties of electronic materials. Electron energy-loss spectroscopy (EELS) in transmission electron microscopy (TEM) gives information on the direct and indirect transitions with high spatial resolution (Egerton, 1996). There are several reports on bandgap measurements of insulators and semiconductors (Batson et al., 1986, Bangert et al., 1997, Rafferty and Brown, 1998, Batson, 1999). Since a bandgap measurement requires high energy resolution, the previous authors employed a cold field-emission gun (CFEG), whose energy spread (>0.25 eV) is smaller than that of a Schottky emitter (>0.5 eV) and those of other thermionic electron sources (>1 eV). Recently, several types of monochromator for a TEM have been developed to reduce the energy spread (Terauchi et al., 1999, Tiemeijer, 1999a, Kahl and Rose, 2000, Mook and Kruit, 2000, Tanaka et al., 2002), and some of them are now commercially available. Several authors have demonstrated the efficiency of monochromators (Terauchi et al., 1998, Terauchi and Tanaka, 1999, Mitterbauer et al., 2003). There is a pioneering study for bandgap measurements (Lazar et al., 2003), but the previous papers mainly focused on core-loss spectroscopy or valence-band spectroscopy.
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