Ground-state core-level energies

In the photoemission spectroscopic method, it is customary to distinguish between a core level region, which is probed in XPS (see Fig. 2), and which contains the response coming from the bound or core levels, and a valence band region, which is explored by both XPS and UPS, and which contains the response coming from the outer electrons in a solid, those of the ground state energy bands. 

The core-level x-ray photoemission spectrum of the Mn 2p core level for (Ga,Mn)As with x = 0.074 was measured and was analyzed by a configuration interaction (Cl) cluster-model assuming a Mn2+ and Mn3+ ground state (Okabayashi et al. 1998). For the d5 configuration, the p-d exchange energy (which is conventionally referred to as Nop for DMS) should be negative and NoP —1.2 eV is obtained for /t-(d5) centers with an optimized parameter set. 

Fig. 12a-e. Non-monopole (quadrupole) relaxation and shape distortion of a core hole in open shell type of situations (a) Lowest order self-energy diagram (b) one-electron picture of the pulling down of empty levels below the Fermi level (c) shape distortion of one-electron orbitals due to quadrupole relaxation (d, e) schematic core level spectra in the case of (d) closed and (e) open ground state shell structure (d)... 

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