I have done X ray Photoelectron Spectroscopy for some of my samples. I am observing a shift of binding energy in Fe 2p peaks and it can be deconvoluted into 4 peaks which is towards higher binding energy for lit reported similar systems. I would like clarify my doubt when to assign the presence of Fe2+ or Fe3+ presence and how to calculate the ratio when both are present. Again I would like to mention the background is noisy compared to the other individual scans in this case so what is the origin of such noisy background?
Thank you Sir this is very useful information. COrrect me if I am wrong the calibration has to be done by adding the shift of C 1s peak to each of the peak observed and further I would also like to mention the binding energies are found to be 714,720,728,734 eV which is at higher side as compared to literature which is 710 and 724 eV for Fe3+ and satellite peak at 719 eV. Could you please suggest some of your useful views.
M. Beisinger and S. McIntyre have published research grade spectra from a series of Iron compounds that you need to help you with your assignments. There is another paper, but I don't remember it just now. Assigning Fe 2+ in the presence of Fe 3+ is difficult. Pure materials are easy to understand by using the complete peak shape if you are using a monochromatic source. You also need to see both the 2p3 and 2p1 peaks together if you use only visual comparison.
Dear Alaka,
You may find some more info regarding your question on another thread at researchgate:
https://www.researchgate.net/post/How_to_set_the_FWHM_full_width_at_half_maxima_for_deconvoluting_the_XPS_spectra?_tpcectx=qa_overview_following&_trid=iBv40i6qELW6uI443qkT0ir9_
Best regards,
John
Alaka, please post the data (graphs?) and give some more details on the measurements. Good reference data are available in Surface Science Spectra - you will certainly find details about Fe, Fe2+, Fe3+ and Fe4+ there ... Good luck, Dirk
Hello Alaka,
Your question is very common to all the beginners who starts using X-ray photoelectron spectroscopy to determine elemental composition on the surface of the samples. I have also faced similar problems when I started it.
As Mr. Tanase has mentioned in their answers, intensity is directly proportional to the concentration of elemental in your sample.
In your Fe2p spectra, de-convolution should be done by considering following points,
1) First you have to select proper baseline which is the most critical parameter to de-convolute any spectroscopy data.
2) Doublet of each oxidation state of Fe i.e. Fe3+ (p3/2, p1/2) and Fe2+(p3/2, p1/2) with 2:1 area ratio and same FWHM considering same peak function (Gaussian-Lorentzian).
3) I think that your spectra does show the presence of satellite peaks. Therefore, this doublet should also be de-convoluted properly.
Thereafter, volume percent of any oxidation state can be calculated by
vol. frac. of Fe2+ = (area of Fe2+ (3/2 and 1/2) peaks)/(area of all peaks)
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