Influence of the core hole on K beta emission following photoionization ororbital electron capture: A comparison using MnO and (Fe2O3)-Fe-55 - art. no. 045109

The Mn K beta fluorescence emission in MnO after photoionization and in (Fe 2O3)-Fe-55 after radioactive electron capture decay from the K shell have b een 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 (Fe2O3)-Fe-55 are shifted in emission energy and are sharper, compared to the spectra following photoion ization in MnO, i.e., the spectra exhibit a dependence on the mode of excit ation. Crystal-field multiplet calculations including ligand-to-metal charg e transfer have been carried out for the 1 s intermediate states as well as for the 3p to 1 s (K beta) radiative transition. The populated I s interme diate states after photoionization are found to be spread over several eV. In comparison, only the lowest-lying Is intermediate states split by the we ak (1s, 3d) exchange interaction are populated after K capture. It is propo sed that the differences in population of the Is intermediate states togeth er with a term-dependent final-state lifetime broadening can account for th e changes in the spectral shapes due to the different modes of excitation.