Abstract :
A detailed first-principles analysis of the L2,3 X-ray absorption near edge structure (XANES) spectra, crystal field strength 10Dq, covalent effects and molecular orbitals (MO) position for all divalent 3d ions from Sc2+ to Cu2+ in cubic ZnS is performed in the present paper. The calculations were done in the framework of the first-principles fully relativistic discrete variational multi-electron (DVME) based on numerical solution of the Dirac equation with the local density approximation. As a result of the performed calculations, the L2,3 XANES spectra for all considered ions were calculated and assigned in terms of the electron configurations involved into the absorption transitions; fairly good agreement with available experimental data for Ti2+, Mn2+, Fe2+, Co2+ and Ni2+ is demonstrated. Experimental XANES spectra for Sc2+, V2+, Cr2+, Cu2+ not reported previously were also calculated for the sake of completeness of the present study to enable a systematic analysis of all calculated results for the whole series considered. It was shown that the L3 and L2 bands shift to the higher energies on increasing a 3d ion atomic number. In addition, the separation between the L3 and L2 bands, the crystal field strength 10Dq and mixture between the 3d ion and sulfur wave functions increase along the considered series, from Sc2+ to Cu2+. On the other hand, all orbitals of the 3d ions systematically lower down in the same direction. The above formulated trends were confirmed by the experimental data on the crystal field splittings and nephelauxetic effect.
