Dear Cissan Adanma Sylvanus ,

please share your EDX spectrum. The Ca and Ag peaks may be superimposed by some of other peaks of higher intensity...

By the way; what is the excitation energy you have used for your EDX analysis?

Best regards

G.M.

Absolutely, share a spectrum if you have such a detailed question. It would also be nice to know more details about your experiment. What levels of Ca and Ag were you expecting? What other elements were identified in the spectrum?

There are some other elements that might overlap and hide those elements, but they are not many. Argon would overlap Ag at 3.0 keV, but I have only seen a few instances of real Ar in sputtered samples. Ca stands out fairly cleanly around 3.7 keV. It could be partially hidden by large amounts of K.

If those peaks are at low levels or if the background is particularly noisy, they might not exceed the threshold for auto-detection. I have also seen cases where the EDS system fails to read the voltage from the SEM and then it fails to identify any peaks.

I suppose that, it can be calculated by means of sum all elements mines all elements of your combine if there is not any overlap between them

I worked on Calcium Aluminum oxide Zinc Oxide reduced graphene oxide thin films while doping with Ni and Ag

I stand corrected. You have a large amount of Sn there which will obscure a small amount of Ag and Ca. (But you didn't say anything about Sn! Why not?)

I also see S and Cl and Si. Where are they from?

That appears to be from an Oxford Inca system. They should have a way of showing you the fit and/or the residuals. That might reveal the missing Ca and Ag intensity.

You certainly can tell the Inca software to quantify the Ca and Ag even if they are small amounts. See what it reports. It might come up with negative intensity/concentration if the levels are low. In that case, there would be no Ag or Ca.

Certainly the uncertainty in the Ag and Ca numbers will be worse than if there was no Sn present.

In cases where elements are not clearly indicated in EDX results, you can account for them by considering several approaches:

1. Ensure that the EDX system is properly calibrated and configured. This includes checking the detector efficiency and resolution, as these factors can affect the sensitivity and accuracy of element detection.

2. Use complementary analytical techniques such as Wavelength Dispersive X-ray Spectroscopy (WDX) or X-ray Fluorescence (XRF) which may offer better detection limits or elemental coverage for the elements not visible in EDX results.

3. Re-examine the processing settings in the EDX software. Adjustments in the peak identification algorithms and background subtraction methods can sometimes reveal or clarify peaks that were not initially apparent.

4. Review the sample preparation method. Inadequate or inconsistent sample preparation can lead to areas where elements are not detected due to surface contamination or uneven topography affecting the X-ray path.

5. Apply statistical methods to analyze the spectrum comprehensively, including minor peaks that might initially be dismissed or overlooked. This can help in identifying trace elements or confirming the presence of elements at the detection limit threshold.

Ali Akbar Firoozi ,

Are you saying these things based on your own experience or are they borrowed from someone else's book or an AI engine?

What you wrote is generally true (it is not wrong), but it is not very helpful. It does not address the specifics.

I will address your points in turn.

1) The calibration seems okay from the spectra that Cissan sent. The resolution is harder to tell. Oxford offers six choices of processing time, 1-6 with 6 giving the best resolution. (I use 4 on our system to get a balance between high throughput and good resolution.

It is unlikely that a higher setting would help given the Sn signal which swamps Ca and Ag.

2) WDS would likely help. XRF might also help if it is based on WDS and not EDS. But where is the nearest WDS system? There is one 15 feet behind me, but it is the only one on the Iowa State University campus and even it is severely underutilized and in danger of being mothballed. Most people will not have access to one. Do you?

3) The EDS processing parameters that you mention are generally not available to the normal user. I would not trust our casual users to try making such changes. They would likely make things worse. But do check the fit and the residuals as you can (as I already suggested).

4) Sample preparation _might_ be an issue. We don't have any images to evaluate the sample condition. I don't think it is an issue of contamination or topography. Topography can be assessed from the background shape, but it looks fairly normal/nominal.

However, if the sample was mounted on ITO- or FTO-coated glass, that would qualify as a sample preparation deficiency. There would be a strong Sn signal from the tin oxide. It could also explain the presence of the Si (from the glass below).

If one is looking for Ca and Ag, xTO glass as a substrate is a very poor choice. Why not use a silicon wafer? It is flatter than xTO glass which does have texture. A Si wafer will contribute only one element to the spectrum and it is away from the elements of interest.

5) Statistical methods will not correct for a a bad setup or measurement.

It is a simple enough thing to explicitly go looking for small bumps from Ca or Ag to see if they might have been missed. You might also explicitly add them to the element list. Let the software see what it can do with the spectrum. Now, if the software indicates a level for them, be careful about trusting it. Be sure to check the sigma value; it will likely be larger than the reported concentration.

You may need to count longer to reduce the effect of the noise on the spectrum. Noise decreases with the square root of the counts, so more x-rays increases the sensitivity to smaller features. You will have to ask what sensitivity or precision do you really need, i.e., what can you afford?

I will also suggest lowering the accelerating voltage. If you are working with thin layers, you do not want the beam to penetrate through your sample more than it has to. You should be able to get by with 8 kV or less. The penetration depth would be 3-4 times less than it would be at 15 kV which would keep more of the beam in your layer.

You would not see the Zn or Ni Ka lines. You would have to use the L lines.

_IF_ there is localized Ca and Sn, you might try using x-ray mapping to see where those elements are. However, you would need Oxford's TruMap function to try to deconvolve the Ca and Ag signals from the Sn signal. Frankly, I don't think it will help in this case since the Sn peak is so large.

Focus on the possible peaks of these elements in literature and finding around these sites or do second type of spectrometry if you found them there than your EDX graph is fack I mean it should show results correspondingly