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peak-like structure. The absorption of X-rays by the Si grid
and Si dead-layer ionizes Si atoms and subsequently results in
the emission of Si K-shell X-rays, which contribute a false Si
peak to the spectrum. In the example for a copper target
shown in. Fig. 16.8, the apparent level of Si contributed by
the internal fluorescence artifact is approximately 0.002 mass
fraction.16.2 “Best Practices” for Electron-Excited
EDS Operation
While modern EDS systems are well supported by computer
automation, there remain parameters whose selection is the
responsibility of the user.16.2.1 Operation of the EDS System
Before commencing any EDS microanalysis campaign, the
analyst should follow an established checklist with careful
attention to the measurement science of EDS operation. To
establish the basis for quantitative analysis, the EDS param-
eters must be chosen consistently, especially if the analyst
wishes to use archived spectra to serve as standards.Choosing the EDS Time Constant (Resolution
and Throughput)
The EDS amplifier time constant (a generic term which may be
locally known as “shaping time,” “processing time,” “resolu-
tion,” “count rate range,” “1–6,” etc.) should be checked. There
are usually at least two settings, one that optimizes resolutionCu_20kV9.95nA300sCu
E 0 = 20 keVCountsPhoton energy (eV)18 000
16 000
14 000
12 000
10 000
8 000
6 000
4 000
2 000
0
0 500 1 000 1 500 2 000 2 500CountsPhoton energy (eV)18 000
16 000
14 000
12 000
10 000
8 000
6 000
4 000
2 000
0
0 500 1 000 1 500 2 000 2 500Cu_20kV9.95nA300s
Residual[Cu_20kV9.95nA300s]. Fig. 16.8 Cu at E 0 = 20 keV. The artifact Si peak is a combination of
the Si K-absorption edge and the Si internal fluorescence peak (peak
fitting in lower spectrum) created by absorption of X-rays in the Si
support grid and the Si detector dead-layer, and subsequent Si X-ray
emissionChapter 16 · Energy Dispersive X-ray Spectrometry: Physical Principles and User-Selected Parameters