On the number, binding energies, and mutual intensities of Ce3d peaks in the XPS analysis of cerium oxide systems: A response to Murugan et al., Superlatt. Microstruct. 85 (2015) 321

I discuss on an XPS analysis of CeO thin films offered by Murugan et al. in a recent article, Superlatt. Microstruct. 85 (2015) 321. I argue that the authors' interpretation is not an accurate picture of the chemical composition of their material, especially not the mapping of the Ce(IV)-Ce(III) redox couple, because such interpretation largely overlooks the quantum mechanics principles and electron correlation phenomena that govern the binding energies and mutual intensities of photoemission peaks in the Ce3d spectrum.