In O 1s spectra, usually the peak near 531 eV belongs to oxygen vacancy sites in oxides, however, in silicates, these peaks are often reported to originate from O-Si. I am confused if the intense peak in the range of 531-532 eV belongs to the oxygen vacancy sites or the O connected to Si.
I think the contribution at about 531 eV should not be interpreted as an "O vacanct" (which by itself often is a wrong definition for an O substitution) nor as a Si-O sub-stoichiometric oxide, that could be found in amorphous Si oxide thin films close to interface with a Si substrate.
Instead, I would investigate the presence of other oxide local compounds such as -Al-O- or oxide-hydroxide phases of transition metal such as Ni or Fe, or some -P-O- phase as well. All of them are possible in phyllosilicates.
Check the following papers to start with:
1. Article Zeolite–Supported Nickel Phyllosilicate Catalyst for C–O Hyd...
2. https://core.ac.uk/download/pdf/129586723.pdf
and also:
http://www.xpsfitting.com/2012/01/common-o-1s-values.html
Hello Debashritar,
the (probably absorption spectrum) near 531 eV is related to an optical transition in oxygen. This means it requires the presence of oxygen. Therefore, principially it cannot related to an absorption by a vacancy.
Nevertheless, the environment of oxygen influences the position of the energy levels of O. Because it is not a transition in free oxygen, it is possible that the energy level of an O-atom near Si is shifted with respect to the O level near a vacancy.
With Regard
R. Mitdank
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