The FWHM and Binding Energy position of O1s might be changed dramatically after thermal tempering, because in some materials the annealing causes the thermostimulated re-arrangement of oxygen sublattice and that is the reason for the changes mentioned.

Also the O 2s will be tranfrormed in this case.

At least in glassy materials....

Regards,

Dmitry

Yes

Thanks for the quick reply. Is there any publications/books that talk about this in more detail ?.

 There are a lot of XPS lectures in the internet written by different researchers. Some of these lectures are presented here. I recommend XPS lectures after Sven Tougaard.

Regards,

Dmitry

In XPS one measures the binding energies of core electrons unlike in UVPES where the binding energies of valence electrons are measured. Chemical changes/changes in interaction strength/changes in crystal structures have a great effect on UVPES binding energies. The effect on XPS will be relatively smaller. As one goes deeper inside the atom the effect of chemical changes/changes in the strength of interactions/crystal structure changes on the binding energies of electrons decreases i.e., the effects become smaller.

Any change in the crystal structure/interactions can have an effect on O 1s and O 2s binding energies. Generally, FWHM depends on the variability of the strength of the interactions. Greater the variability in the strength of the interactions, greater will be the FWHM.

Generally at low temperatures the variations in the strength of the interaction will be larger, but at higher temperatures the variability in the strength of interaction decreases, leading to narrower FWHM (of course it depends on the sample). For example, a material can exist in amorphous form or polycrystalline form at low temperatures. Since there are many different chemical environments, FWHM will be larger. But at high temperatures the material may exist as a single crystal having very similar chemical environments leading to narrower FWHM.

Another example, a single atom bonded to different atom types (different chemical environments) at different locations will have different binding energies. But when the same atom is bonded to the same atoms at different locations (same chemical environments) will have same binding energies.

Summary: Greater FWHM for a single atom means greater range of binding energies and the binding energies vary due to the chemical environment. Chemical environment changes due to changes in bonding pattern like changes in crystal structures or reactions of atoms with other groups or variation in the strength of the interactions.

FWHM changes in XPS relate to chemical bonding, and this can change within thermal processing.

Here it is written very good using accepted theoretical background (p.275, intrinsic and extrinsic reasons for variations in FWHM of XPS spectra). The most common reasons in materials science for variations  in FWHM I told to You earlier.

Regards,

Dmitry

Thank you very much for all the help so far !!