I have performed XPS analysis of my samples to get chemical state in which each element is present. I had given the samples to a third party lab. The operator has provided me with an excel sheet and I am attaching a picture of the peak table here. I have no prior experience in analysing XPS data and am having a hard time in deciphering the chemical state of each element.
The operator has given me the fitted data for each element and binding energy range for each element. I was under the assumption that I just need to compare the peak binding energy of each element to the reference databases available. But for my peak binding energy/energies there is not reference chemical state for that element.
For eg. For Pt 4F5/2 orbital, peak BE is 74.76 but there is no reference chemical state for this Pt with this orbital. I tried searching in open sources databases and in literature. In this case, according to papers there can be a shift depending on the chemical environment surronding the atoms but how to decipher this information i.e what shift is happening and due to what?
Any help or any link to any good literature which illustrates the process of finding chemical state of elements from fitted data will be highly appreciated.
The NIST database has actual references for Pt4f5/2: https://srdata.nist.gov/xps/EngElmSrchQuery.aspx?EType=PE&CSOpt=Retri_ex_dat&Elm=Pt
However, one thing seems odd to me: for Pt4f7/2 the operator has received a negative intensity, this makes me sort of doubt the baseline subtraction performed here, so it would make sense to have a look at the actual spectrum. If you want to analyze chemical states, you have to check the peak shape either weay since you have to verify how many species there actually are.
Dear Omkar Kedge ,
Have the results been corrected against C1s? In the table you show, C1s shows a peak at 285.84 eV, which makes me think that the spectra are not corrected. In order to evaluate the oxidation state, EVERYTHING must be corrected beforehand...
Best,
Fran
Francisco Manuel Marquez No, the C1s correction method itself is not a good method. The "standard" value of 284.6eV is consider "applicable" for adventitious carbon but here you have stoichiometric amounts so this would be something else even when you consider the method itself valid.
However, it has been shown quite clearly that this "correction" creates more errors than it fixes:
https://www.researchgate.net/project/Why-you-should-not-use-the-C-1s-peak-for-referencing-XPS-spectra
Dear Dr. Ganeshan, the picture file looks like a final result. What about the original data? Did the operator give you or not ?
If they gave it you can fit it and there is a database available from that you can find the charge state of the element present in the compound.
Dharmadoss Sornadurai sir, I have recieved the raw data files from the operator. Could you suggest any good resources which might help me in figuring out the fitting process?
Any help will be appreciated.
The CasaXPS manual is really helpful for that even if you don't have CasaXPS:
http://www.casaxps.com/help_manual/manual_updates/peak_fitting_in_xps.pdf
Omkar Kedge I have attached a PPT file which will guide you to proceed still if you could not send me the message.
with regards
D. Sornadurai
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