Oxidation state and chemical shift investigation in transition metal oxides by EELS

► The chemical shifts of V/Mn/Fe-L(2,3) and O-K edges were recorded with high accuracy. ► The TM-L edge ELNES is similar both in peak shape and position at the same valence. ► Various methods are studied and discussed to measure TM valence by EELS. ► The V/Mn-L(2,3) onset energy is linearly related to the valence of the transition metals. ► The superior methods demonstrate the importance of the absolute peak position.