My samples are thin films containing Fe element. The Fe atomic% measured by EPMA is much higher than that measured by EDS mapping.
For discussion it's better to see your results. By the way, was your thin film of constant thickness? The same for both methods?
Vladimir Dusevich Thank you, sir. My film thicknesses are constant and I have measured both EDS and EPMA on the same sample. The relative amount of Fe measured by EPMA has increased to 0.88 compared to the 0.7 measured by EDS. The other samples were similar to this. Is this just because of the different measurements?
Hi Sophia,
The discrepancy you're observing between the Fe atomic% measured by EPMA (Electron Probe Microanalysis) and EDS (Energy-Dispersive X-ray Spectroscopy) mapping could be due to several factors:
1. Spatial Resolution: EPMA typically offers higher spatial resolution than EDS mapping. This can lead to more accurate and localized measurements of elemental composition. EDS mapping, on the other hand, might be affected by the larger probing volume, resulting in more averaged values.
2. Quantification Methods: EPMA and EDS may employ different quantification methods to determine elemental composition. EPMA often uses standards-based quantification, which can be more accurate if suitable standards are used. EDS mapping, depending on the software and settings, might rely on elemental intensity ratios, which can sometimes introduce errors, especially if the sample's composition varies significantly.
3. Sample Preparation: Thin films can be susceptible to surface contamination, thinning, or unevenness. These factors can impact the accuracy of elemental analysis. EPMA might be less affected if it's performed on a small area with minimal sample preparation.
4. X-ray Interactions: EDS measures X-rays emitted from the sample due to electron interactions. The X-rays can escape the surface and interact with the surrounding material before reaching the detector. This can lead to X-ray path length variations, causing issues in quantification, especially for thin films.
5. Matrix Effects: The presence of other elements in the sample matrix can affect the X-ray emissions and the ability to accurately quantify the Fe content. EPMA might handle these matrix effects differently from EDS.
6. Detector Efficiency: The detectors used in EPMA and EDS systems might have different efficiencies for detecting X-rays of different energies. This can impact the quantification accuracy.
To address the discrepancy, you might want to consider using standard reference materials with known compositions for both EPMA and EDS analysis. Additionally, optimizing the experimental parameters and conducting a thorough assessment of sample preparation methods could help improve the consistency between the two techniques.
Hope this helps,
Kind regards
Dear Ameer K Ibraheem ,
Thank you so much for your answer. I read your reply carefully. It looks full of professional knowledge. This is really helpful.
Best regards,
Sophia
Dear Ameer K Ibraheem ,
1. Spatial resolution is the same for EDS and WDS (sometimes called EPMA). It's the same electron beam.
2. Here I do agree, standardless is not too reliable. However WDS software may employ standarless approach too, as well as EDS may utilize standards.
3. Sample preparation was the same.
4, 5. The same thing for both methods.
6. Detector efficiency should be accounted during quantification, so it is not important.
Dear Sophia Morley , as was mentioned by Ameer K Ibraheem , there are two methods of X-ray quantitive analysis - standardless and with standards. If you used standardless EDS and WDS (EPMA) with standards, you can safely discard EDS results as less reliable. However, 0.70% and 0.88% are pretty close results for X-ray microanalysis (EDS and WDS). If your aim is to compare both methods, you may want (actually, you must) to take a statistical approach, to acquire results for multiple spots. Theese small differences may be due to non homogeneity of your thin film, surface roughness, variations in thickness, etc.
Vladimir Dusevich Why do use Chatgpt to answer question? Either your answer is one liner or chatgpt generated. Very shame on Vladimir Dusevich University of Missouri dont have any knowledge of the field.
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