Electron microscopy
 
Pile-up Continuum in X-ray/EDS Profiles
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At high count rates, a pile-up continuum can appear in EDS spectra as a tail on the high energy side of peaks. [1] Figure 1238 employed the same theoretical background modeling program to subtract the EDS backgrounds. However, Figure 1238 (a) shows a good background fit to the spectrum taken at a modest count rate, while the spectrum taken at a high count rate shown in Figure 1238 (b) exhibits strong pile-up effects and thus, the background modeling provides a very poor background subtraction.

Spectra from pure Cobalt standard obtained at 20 kV: (a) at a modest count rate and (b) at a high input count rate
(a)
Spectra from pure Cobalt standard obtained at 20 kV: (a) at a modest count rate and (b) at a high input count rate
(b)
Figure 1238. Spectra from pure Cobalt (Co) standard obtained at 20 kV: (a) at a modest count rate and (b) at a high count rate. Adapted from [2]

Table 1238. Pile up continuum and sum peaks.

Characteristic Peak width (FWHM) Pile up continuum Sum peaks
Short Processing time Wide peaks   Less
Long Narrow peaks   More
  Count rate   Occurs at high count rates  
High   Pile up continuum can appear as a tail on the high energy side of peaks May appear at the end of the tail
X-ray photons   Significant for high energy photons  

 

 

 

 

 

 

[1] P. J. Statham, Pile-Up Rejection: Limitations and Corrections for Residual Errors in Energy-dispersive Spectrometers, X-Ray Spectrom. 6 (2), 94-103 (1977).
[2] Peter J. Statham, Limitations to Accuracy in Extracting Characteristic Line Intensities From X-Ray Spectra, J. Res. Natl. Inst. Stand. Technol. 107, 531–546 (2002).

 

 

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