2.3.5. X-ray photoelectron spectroscopy (XPS)
The XPS analysis was performed using a Thermo Scientific KAlpha X-ray photoelectron spectrometer equipped with an Al K˛
(1486.6 eV) X-ray source. Survey spectra were measured in the
range from 0 to 1100 eV with pass energy of 200 eV. A highresolution spectrum for Mn 2p was measured with pass energy of
50 eV. For each case, 10 scans were performed. Binding energies
were measured with a precision of ±0.1 eV. Surface charge compensation was performed using a low energy electron flood gun.
All binding energies were referenced to the C 1 s line at 285.0 eV.
Photoelectrons were collected at 90◦ with respect to the sample
surface. The analysed area had a diameter of400 m. The base pressure in the analysis chamber was approximately 2 × 10−8 mbar. The deconvolution ofthe XPS spectra for the Mn 2p levels was made by
commercial peak fitting software (XPSPeak 4.1).