Dear William Richards ,

EDX based on electron beam excitation is quite surface sensitive in the range of up to only a very few µm in maximum (depending on the electron energy).

See for example:

https://www.globalsino.com/EM/page4795.html

A finger print residue is placed just at the sample surface and the primary electron beam does not suffer from any attenuation prior to interacting with the residue. Furthermore the 'self' attenuation of the C characteristic radiation is only due to low Z elements in the residue.

The question here is: what is the thickess (or better mass coverage) of a finger print residue. The answer found is at the end of the introduction part of:

Article The deposition of fingerprint films

to be around 0,1µm.

From that value I would expect that a fingerprint residue might cause that quite high C amount in your EDX analysis. Unfortunately I have got no experience by myself at that low energy regime.

But you may ask our RG-colleague Vladimir Dusevich via RG messenger. He is very experienced in these things...

(https://www.researchgate.net/profile/Vladimir-Dusevich)

Best regards

G.M.

Off the top of my head, Carbon contamination on metals often can be traced back to cracking by the electron beam of organic materials that have not been cleaned off the surface (fats, proteins...). 20 to 25% is quite high however.

Try to clean the surface of the metal using solvent and run the analysis again ?

Would your metal have been varnished ?

The metal is Kanthal and unfortunately I don't have time to test the bulk material before my submission, my current theory is that the Carbon is soot from the processing of the wire.

Of course it could be that "the Carbon is soot from the processing of the wire" and gives carbon radiation. Vapers do "dry burn" new kanthal wire, heating it to red-yellow temperature, to get rid of organic contamination (it goes off with smoke). But one measurement is never enough to give a reliable explanation.

Typically, fingerprints contain other elements, like electrolytes, in addition to C. If I'm trying to determine if something might be a fingerprint, I also look for low levels of O, Na, and Cl. May also see K and S.

Although everything mentioned above stands true and is correct...are you sure that this percentage does not represent an area of the carbon tab you used to hold your sample still ? Maybe the "zoomed in" region you run EDS on, contained a part of it, so you got it in your results and/or maybe you can attribute it likewise to your report. William Richards

So, if you have used the carbon tape on the substrate holder to test the sample surface in SEM, thereby EDX, a higher carbon content may be possible from that. Basically, carbon peaks occur, and due to this reason, there is a highly intense peak. I also faced the same issue while performing EDX with my sample.

Dear Mohd Rehan Ansari , unfortunately your answer is wrong.

Vladimir Dusevich Who do you think you are? Why are you using Chatgpt and policing others like an autocrat? Stop using Chatgpt to answer questions/ You are unfortunate Vladimir Dusevich using chatgpt.