Electronic and crystal-field effects in the fine structure of oxygen-K electron energy-loss spectra of LaxCa1-xMnO3 ...

The fine structure of oxygen-K electron energy-loss spectra (EELS) of transition-metal oxides is known to correlate with nominal oxidation states (NOS) that are often interpreted as charge states. Here we report calculations of O-K EELS in LaxCa1-xMnO3 that agree with measured spectra and show that the variation of the pre-peak��s intensity with doping is controlled by the orbital occupancy of the majority-spin Mn 3d states while its width is controlled by crystal-field splitting. The results confirm that the NOS extracted from EELS correlates with orbital occupancies but does not probe physical charge.