Analysis of elemental oxidation states in XPS relies on the determination of binding energies based on a suitable reference.  Most samples encountered are inherently insulating and so a suitable internal reference is chosen to reference all energies to.

Typically the carbon core level for adventitious carbon, C(1s) is used and assigned a value of 284.8 eV, although 285.0 eV is also commonly used, especially in the XPS of polymers.

Here, we provide a list of common binding energies, for a number of standards run in our lab and (unless otherwise stated) referenced to C(1s) at 284.8 eV.