Oxygen 1s for Transition Metals

The O 1s BE and FWHM values obtained for the standard Sc, Ti, V, Cu and Zn samples[1] are presented in Table 1. The O 1s BE and FWHM values obtained for the standard Cr, Mn, Fe, Co and Ni samples[2] are presented in Table 2.

For many of the pure oxide samples there is a second higher BE peak that can be ascribed to contributions from a defective oxide component inherent in these oxide surfaces as suggested previously10. Other work has shown that this is a defective oxide peak and not hydroxide as the presence of hydroxide has been ruled out by other methods[3,4]. For all of the oxides studied here this peak has an area contribution between 20 and 40 % consistent with other powdered oxides including nickel[5] and chromium[6]. These contributions from defective sites are unlikely to compromise the assignment of chemical states. It should be noted that this second peak could result from carbonates species. Inspection of the C 1s spectrum should confirm if this is occurring.

Pure oxide samples were not heated to remove possible surface hydroxides before analysis to avoid reduction of the oxide. In one related experiment in this laboratory with MnO heated to 600°C for 12 h, there was no significant change in the higher BE component ascribed to defective oxide, indicating little or no surface hydroxides are present.

Table 1. Selected O 1s values for Sc, Ti, V, Cu and Zn compounds [1].

Table 2. Selected O 1s values for Cr, Mn, Fe, Co and Ni compounds [2].

References:
[1] M.C. Biesinger, L.W.M. Lau, A.R. Gerson, R.St.C. Smart, Appl. Surf. Sci. 257 (2010) 887.
[2] M.C. Biesinger, B.P. Payne, A.P. Grosvenor, L.W.M. Lau, A.R. Gerson, R.St.C. Smart, Appl. Surf. Sci. 257 (2011) 2717.
[3] H.A.E. Hagelin-Weaver, J.F. Weaver, G.B. Hoflund, G.N.Salaita, J. Electron Spec. Rel. Phenom. 134 (2004) 139.
[4] P.R. Norton, G.L. Tapping, J.W. Goodale, Surf. Sci. 65 (1977) 13.