I have modified a sample with two different materials. The other results in a positive shift in the BE of the 2p peaks while the other results in a negative shift. what do this shifts mean?
I would add to Artur's excellent answer and state that charge correction (usually by reference to the C 1s 285 eV peak) is assumed to have occurred before consideration of oxidation state of that element
Thank you for your replies. I have actually performed charge corrections with reference to the C1s at 285 eV before and that is when I observed the shifts thereafter
Dear Macheli, I agree with the above answer. The main cause of the peak shift in XPS spectra is mostly related to chemical shifts due to the presence or absence of the chemical states of the element having different formal oxidation state. And the intensity may also be changed bcos it is directly linked to the number of atoms in the respective chemical state. So I think your samples have various formal oxidation states which may be due to your modification process.
I am adding my opinion for this question as it falls under my area of research. I recommend the answer of Gaurav Malik. Observed peak shift may be ascribed to the characteristic change in the physical or chemical environment of the analyzed species.
Regarding the charge corrections and referencing to C 1s at 285 eV I would recommend reading this:
https://www.researchgate.net/project/think-twice-before-you-use-C-1s-as-a-binding-energy-reference-in-your-XPS-work
The binding energy peak position of an specific element depends on the oxidation state and local chemical environment of that element. In the case of modifying a sample by adding other elements, if the electronegativity of the doping element is higher than the base element, the electron density around the base element decreases and the binding energy increases. therefore, binding energy peak shifts positively. Conversely, if the electronegativity of the doping element is lower than the base element, the electron density around it increases and the binding energy decreases, leading a red shift in BE peak position.
So, is it possible to a 5eV shifting in the peaks of amorphous coatings with different oxygen levels?
Taha Cagri Senocak More information required. What is the nature of the coating(s)? Metallic/polymeric etc? I'm also assuming charge correction.
The peak positions may shift by small amounts due to the chemical nature of the neighboring atoms on an individual surface.
Mr. Seyed Mohsen Adyani could you please send me the supporting reference for that. or suggest any online resource for detail study.
The XPS Peak shift is either caused by the charging effect on the sample surface. or it varies with the change in surrounding. The binding energy varies with the change in shielding effect.
The charging effect is beautifully explained in this video link given below -
https://www.youtube.com/watch?v=AJ-T8uAGsMk
The peak positions of the functional groups have been described well in the literature (Wagner, C. D., Riggs, W. M., Davis, L. E., Moulder, J. F. & Muilenberg, G. E. Handbook of X-ray Photoelectron spectroscopy). However, the peak positions may shift by small amounts relative to those indicated in the literature due to the chemical nature of the neighboring atoms on an individual surface.
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