Low energy resolution

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Manganese resolution
Low energy resolution
Fluorine resolution
Incomplete charge collection
Carbon resolution
Fe55 source
Changes with time
Geometry
Summary

What makes a good detector?

The importance of low energy resolution

The identification and quantification of closely spaced X-ray peaks becomes easier and more accurate as the separation between them increases. X-ray lines get closer together at low energy and this is apparent in Fig. 6 where the energy of the main alpha line for K, L and M series is plotted for all elements. At the MnKα energy most commonly used to specify EDS resolution, peaks are well separated. However, it is clear that much more serious overlaps occur below 3keV and the resolution performance at low energies is critical to good performance for all elements.

When small features <1µm in size are being analyzed, the beam voltage needs to be reduced to avoid electron scattering outside the feature. However, at low kV only low energy lines are available for analysis. Spectra collected from a nickel alloy at 20kV and 5kV (Fig. 7) illustrate the importance of resolution at low energy. When working at 20kV, the separation of widely spaced K lines of Cr, Fe and Ni, will not be affected much by a few eV variation in resolution. When working at 5kV however, where identification relies on L lines, a detector with a few eV better resolution will allow the L lines of Cr, Fe and Ni to be separated enough for confident identification.

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