We present a detailed analysis of the photoemission (PE) spectra of Mg 2p shallow core-level in the Zn2Mg crystalline Laves phase and in the icosahedral ZnMgRE quasicrystals. The PE measurements were performed on in situ cleaved single-grain samples at the Swedish synchrotron-radiation facility MAX-lab. The PE spectra were recorded at low, 90–150 K, temperature in the spectral range of 60-130 eV with the energy resolution of about 0.1-0.3 eV.
Analysis of the Mg 2p photoemission spectra in magnesium dizinc reveals a distinct variation of the Mg 2p lineshape with the photon energy due to a manifestation of the surface-shifted Mg 2p component. The evaluated surface-shift of the level is of about -0.12 eV. The deduced dependence of the electron mean free path on the electron energy is in agreement with literature data for other solids.
The Mg 2p level in ZnMgRE quasicrystals is essentially affected by the coordination field of neighbouring atoms. The coordination field induce both different coordination shifts of the level at different inequivalent magnesium sites of the quasicrystalline lattice [1], and splittings of Mg 2p spin-orbit components. The coordination field at different inequivalent Mg sites was calculated by the Ewald-Fuchs method. The coordination-induced fine structure of the level was calculated by solving the secular equation in the basis of atomic p-orbitals. Results of the calculations predict the coordination shifts of the Mg 2p level of about 0.26 eV and splittings of the spin-orbit doublet p3/2-component of about 10 meV. The theoretical Mg 2p lineshapes simulated nicely fit experimental PE spectra.
[1] V. Karpus, A. Suchodolskis, U. O. Karlsson, G. Le Lay, L. Giovanelli, W. Assmus, S. Brühne, and E. Uhrig, Appl. Surf. Sci. 252, 5411 (2006).
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