Core electron excitation energy level diagram

Figure 3. Energy level diagram illustrating chemical shifts of the core levels and different final state configurations that can be reached by core electron excitation.

Fig. 2.8. Energy level diagrams for Cu, Ag and Au, all of which have one outer electron, drawn so as to emulate the trend for the alkalis. Note that the ordering of the atoms does not follow atomic numbers, and that core-excited configurations (plotted as circles and denoted with a star) appear amongst the low-lying excited Rydberg states (based on data from C.E. Moore [23]).

In the example illustrated in the diagram, the atom is raised into an excited state by the creation of a core hole at level L3. An electron then falls down from a higher level (level Mi in the diagram) to fill this core hole, and the excess energy is carried away as the kinetic energy of a further electron which is emitted from the atom (in this case from level M2 3). 

The ZSA phase diagram and its variants provide a satisfactory description of the overall electronic structure of stoichiometric and ordered transition-metal compounds. Within the above description, the electronic properties of transition-metal oxides are primarily determined by the values of A, and t. There have been several electron spectroscopic (photoemission) investigations in order to estimate the interaction strengths. Valence-band as well as core-level spectra have been analysed for a large number of transition-metal and rare-earth compounds. Calculations of the spectra have been performed at different levels of complexity, but generally within an Anderson impurity Hamiltonian. In the case of metallic systems, the situation is complicated by the presence of a continuum of low-energy electron-hole excitations across the Fermi level. These play an important role in the case of the rare earths and their intermetallics. This effect is particularly important for the valence-band spectra. 

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