Valence state of transition metals, e.g. in the positive electrode and charge transfer during lithiation and delithiation processes in Li-ion battery materials, can be analyzed by measuring the relative intensity of the transition metal L₃ and L₂ lines. In order to determine the oxidation states of 3d and 4d transition metals in unknown oxides or alloys, EEL spectra at the L₃/L₂ edge of white-lines can be recorded from known (standard) specimens first.

In the analysis of valence states based on white-lines in EELS, the accuracy of the determination of the ratios of the two valence states (e.g. Ce⁴⁺/Ce³⁺ for cerium) depends on the ability to separate the contributions of the two oxidation states. Table 2643 lists the M₅ to M₄ area and branching ratios of Ce-bearing materials and Figure 2643a shows the simulated peaks originated from Ce⁴⁺ and Ce³⁺ valence states.

Table 2643. The M₅ to M₄ area and branching ratios of Ce-bearing materials. [1]

                     ^aM₅/M₄ branching ratio is defined as the intensity ratio I…(M₅)†/[I…(M₄)† + I…(M₅†Š)].

The Ti L_2,3 near-edge structures in EELS spectrum for Ti³⁺ and Ti⁴⁺ are different as shown in Figure 2643b. Here the blue curve shows the fine structure of Ti³⁺ state , while the red curve shows the fine structure of Ti⁴⁺ state. The doted curve is an experimental data from a mixture of SrTiO₃ (with Ti⁴⁺) and LaTiO₃ (with Ti³⁺) materials and thus can be decomposed into a linear combination of Ti³⁺ and Ti⁴⁺.

Figure 2643b. The Ti L_2,3 near-edge structures in EELS spectrum for Ti³⁺ and Ti⁴⁺. Adapted from [2].

[1] L.A.J. Garvie and P.R. Buseck, Determination of Ce4+/Ce3+ in electron-beam-damaged CeO2 by electron energy-loss spectroscopy, Journal of Physics and Chemistry of Solids 60 (1999) 1943–1947.
[2] A. Ohtomo, D. A. Muller, J. L. Grazul and H. Y. Hwang, Artificial charge-modulation in atomic-scale perovskite titanate superlattices, Nature 419, 378-380 (2002).