We have analyzed XPS spectra of commercially bought WS2 powders and want to see if our fitting is correct. So, what is the reported stoichiometry of natural WS2?
For serious: I've just checked and the only source of natural Tungstenite is some place in Italy (Crevola d´Ossola), apparently. I do not think anyone ever bothered to do XPS on this and why would they? If you have commercial, purified WS2 your stoichiometry is well-defined, in the natural minerals you will just observe trace elements that decrease your analytic quality.
So if your analysis of the commercial WS2 did not yield the stoichiometry WS2 you either have to augment your analysis or your commercial provider.
I completely agree with Jürgen Weippert . Why do you think that it is different? Did not you determine stoichiometry W/S = 1/2? Did you multiply individual integrals by Relative Sensitivity Factors (R.S.F.)?