Mn 3s Peak Separation Values

In addition to curve-fitting of the Mn 2p spectrum, the Mn 3s peak (if available) can also provide useful insight into the Mn oxidation state of an unknown sample.  The Mn 3s peak is split into two peaks and the peak separation may be used to elucidate oxidation state.  Peak separation ranges are presented below. 

From [1] for oxides.
Mn(II) 5.7-6.2 eV
Mn(III) 4.6-5.4 eV (4.6 for MnOOH, Mn2O3 selected values were  5.2-5.4 eV)
Mn(IV) 4.5-4.7 eV

The trends are less convincing when you look at a wider set of data that includes various other ligands[2].  The ligand-Mn bond degree of covalency effects the peak separation [1,3]. Use caution when other Mn compounds are possible.
Mn(0) 3.7-4.2 eV
MnO 5.5-6.1 eV
MnOOH 4.6 eV
Mn2O3 5.4-5.5 eV
Mn3O4 5.3-5.4 eV
MnO2 4.5-5.5 eV
MnF2 6.3-6.5 eV
MnF3 5.6 eV
MnS 5.3 eV
MnS2 5.5 eV
MnCl2 6.0 eV
MnBr2 4.8 eV

As recent article from Eugene Ilton[4] tests of the use of the Mn 3s splitting values as a means to determine oxidation state and shows it to be not of great value (i.e. doubt is cast on its usefulness).

[1] J.L. Junta, M.F. Hochella Jr., Geochimca et Cosmochimica Acta, 58 (1994) 4985-4999.
[2] C.D. Wagner, A.V. Naumkin, A. Kraut-Vass, J.W. Allison, C.J. Powell, J.R.Jr. Rumble, NIST Standard Reference Database 20, Version 3.4 (web version) (http:/ 2003.
[3] A.J. Nelson, J.G. Reynolds, J.W. Roos, J. Vac. Sci. Technol. A 18(4) (2000) 1072-1076.
[4] E.S. Ilton, J.E. Post, P.J. Heaney, F.T. Ling, Appl. Surf. Sci. 366 (2016) 475.