Influence of the core hole on Kß emission following photoionization or orbital electron capture: a comparison using MnO and 55Fe2O3

Abstract

The Mn K ß fluorescence emission in MnO after photoionization and in "Fe 2 O 3 after radioactive electron capture decay from the K shell have been measured using a crystal array spectrometer with an instrumental energy bandwidth of 0.7 eV (full width at half maximum). Both compounds have a 3d 5 valence electron configuration in the ionic approximation. It is found that the spectral features after K capture in 55 Fe 2 O 3 are shifted in emission energy and are sharper, compared to the spectra following photoionization in MnO, i.e., the spectra exhibit a dependence on the mode of excitation. Crystal-field multiplet calculations including ligand-to- metal charge transfer have been carried out for the 1s intermediate states as well as for the 3p to 1s (K ß) radiative transition. The populated 1s intermediate states after photoionization are found to be spread over several eV. In comparison, only the lowest-lying 1s intermediate states split by the weak (1s,3d) exchange interaction are populated after K capture. It is proposed that the differences in population of the 1s intermediate states together with a term-dependent final-state lifetime broadening can account for the changes in the spectral shapes due to the different modes of excitation.