Do elemental peaks on SEM-EDS spectra relate to concentration

In summary, the conversation discusses the difficulty of obtaining accurate quantitative results using EDS spectrum analysis. It is recommended to use a spectrum with good signal to noise ratio and to use ZAF correction factors with accurately determined standards. However, even with these precautions, it can be difficult to achieve results with high accuracy.
  • #1
rawr18
3
0
Hello,

I recently did an experiment where I examined and analyzed crystals using SEM-EDS. One of the major parts of my experiment was to determine the concentration of a certain element (calcium) in the different crystal samples. I noticed that some calcium peaks were higher than others. Does this relate to concentration at all?

Thanks
 
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  • #2
EDS spectrum analysis can be notoriously difficult when you want quantitative results. Do a search on 'quantitative EDS' - lots of things to learn about.

The short of it is that you typically want to use a spectrum with good signal to noise ratio, collected with a sampling rate that minimizes various sampling errors, and quantitate the spectrum using ZAF correction factors using standards whose compositions are accurately determined using other techniques.

Generally speaking, it's very difficult to get results within 20% accuracy, and often the results can be off by much larger factors.
 

1. How are elemental peaks on SEM-EDS spectra related to concentration?

The presence and intensity of elemental peaks on SEM-EDS spectra are directly related to the concentration of that particular element within the sample.

2. Do all elements present in a sample show peaks on SEM-EDS spectra?

No, not all elements present in a sample will show peaks on SEM-EDS spectra. Some elements may be present in very low concentrations or may not emit characteristic X-rays, resulting in no peaks on the spectrum.

3. Can the concentration of an element be quantitatively determined from SEM-EDS spectra?

Yes, the intensity of peaks on SEM-EDS spectra can be used to calculate the concentration of elements present in a sample. However, this requires calibrated standards and proper quantification methods.

4. Are there any factors that can affect the accuracy of concentration measurements from SEM-EDS spectra?

Yes, there are several factors that can affect the accuracy of concentration measurements from SEM-EDS spectra. These include matrix effects, beam damage, and overlapping peaks from different elements.

5. Is it possible to identify a specific element based on its peak position on a SEM-EDS spectrum?

Yes, each element has a unique peak position on a SEM-EDS spectrum, known as its characteristic X-ray energy. By comparing the peak position of unknown elements to known standards, it is possible to identify the presence of specific elements in a sample.

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