This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.

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Pearson et al. [1] experimentally and theoretically (based on one-electron Hartree-Slater calculations) found that the intensities of L_2,3 white lines for most of the 3d and 4d transition metals decreased nearly linearly with increasing atomic number, reflecting the filling of the d states. Figure 4770a shows the deconvoluted and background-subtracted L_2,3 energy-loss spectra for the 3d transition metals. The edge energies are not shown in order to present all the spectra in the same figure, while the intensities of the white lines are scaled simultaneously for all elements.

Figure 4770a. The deconvoluted and background-subtracted L_2,3 energy-loss spectra for the 3d transition metals. [1]

The L_2,3 ELNES of Fe (Fe²⁺ and Fe³⁺) shows multiplet structures of valences representing valence fingerprints. More than one valency and coordination of Fe is often present in the same material, e.g. mineral. Minerals containing Fe²⁺ and Fe³⁺ are most commonly octahedrally coordinated, although Fe in tetrahedral coordination is sometimes found. The splitting of the L₃ edge gives the signature of multiple valence states in mixed valence Fe-bearing minerals. Figure 4770b shows energy-loss spectrum of an iron fluoride film, taken with TEM-EELS system.

Figure 4770b. Energy-loss spectrum of an iron fluoride (FeF₂) film: (a) low-loss region with a logarithmic intensity scale and
(b) part of the core-loss region, with linear vertical scale. Modified from [2]

Peaks: Low-loss, including zero loss (first peak), which is the most intense
          Prominent low-loss peak, centred around 22 eV (resulting from a plasma resonance of the valence electrons)
          54 eV edge due to inelastic scattering from inner-shell electrons [M₂ andM₃ subshells (3p^1/2 and 3p^3/2 electrons) of iron atoms]
          L₃ and L₂ edges (representing excitation of Fe 2p^3/2 and 2p^1/2 electrons).

In Figure 4770c, the Fe L_2,3 edges from leucite (Fe³⁺), hematite (Fe³⁺), siderite (Fe²⁺), and chromite (Fe²⁺) show different edge shapes. [3]

Figure 4770c. The Fe L_2,3 edges from leucite (Fe³⁺), hematite (Fe³⁺), siderite (Fe²⁺), and chromite (Fe²⁺). [3]

Figure 4770d shows Fe L_2,3 edges from three phyllosilicates: nontronite (dominantly Fe³⁺), cronstedtite (Fe²⁺ and Fe³⁺) and the chlorite daphnite (dominantly Fe²⁺ with a few percent Fe³⁺).

Figure 4770d. Fe L_2,3 edges from three phyllosilicates. [3]

Table 4770a shows the energies (eV) of the Fe L₃ and L₂ edge peak maximum of some materials and the separation of the L₃ and L₂ peak maxima because of spin orbit splitting.

Table 4770a. The energies (eV) of the Fe L₃ and L₂ edge peak maximum of some materials and the
separation (ΔE_L2,3) of the L₃ and L₂ peak maxima.

Figure 4770e shows EEL spectrum for pure iron (Fe) showing the isolated white line intensities and the normalization energy window 50 eV width. This signal isolation presents a method to remove the background of the measured spectrum.

Figure 4770f shows EEL spectra of TiO₂, V, Cr, Fe₂O₃, CoO, NiO, and Cu with L_2,3 energy-losses for the 3d transition metals. The chemical shift of O element in the different oxides (TiO₂, Fe₂O₃, CoO, and NiO) is also indicated in the figure. The main edges of Ti, V, Cr, Fe, Co, Ni and Cu, and their edge onsets are listed in Table 4770b.

Table 4770b. Main edges of Ti, V, Cr, Fe, Co, Ni, and Cu, and their edge onsets.

[1] D. H. Pearson, C. C. Ahn, and B.Fultz, White lines and d-electron occupancies for the 3d and 4d transition metals, Physical Review B, 47(14), (1993) 8471-8478.
[2] Electron energy-loss spectroscopy in the TEM, R. F. Egerton, Rep. Prog. Phys. 72, 016502, 25 (2009).
[3] Laurence A. J. Garvie, Alan J. Craven, Use of electron-energy loss near-edge fine structure in the study of minerals, American Mineralogist, 79, (1994) 411-425.
[4] Pearson, D. H. and Fultz, B. and Ahn, C. C. Measurements of 3d state occupancy in transition metals using electron energy loss spectrometry. Applied Physics Letters, 53 (15), (1988) 1405-1407.