X-ray MnKβemission spectra of manganese oxides and manganates

Abstract

X-ray Mn $K\ensuremath{\beta}$ emission spectra of metallic manganese, MnO, ${\mathrm{MnO}}_{2}$, ${\mathrm{K}}_{2}$Mn${\mathrm{O}}_{4}$, and ${\mathrm{KMnO}}_{4}$ are accurately measured by the fluoresecent excitation method using a two-crystal spectrometer. The results show that molecular-orbital theory provides a suitable interpretation for x-ray $K\ensuremath{\beta}$ emission spectra of the manganese oxides and manganates. The valence bands of the manganates are mainly composed of the $4p(\ensuremath{\pi},\ensuremath{\sigma})$ characters of the molecular orbitals for tetrahedrally coordinated ${\mathrm{MnO}}_{4}^{\ensuremath{-}}$, while the valence bands of the manganese oxides are composed of mainly the $4p(\ensuremath{\pi})$ and $4p(\ensuremath{\sigma})$ characters, and also the $3d(\ensuremath{\pi},\ensuremath{\sigma})$ characters of the molecular orbitals for octahedrally coordinated oxides. These characters give rise to the structures in the valence band of the manganese oxides. The peak $A$, which is observed in the spectra of the manganese compounds, is ascribed to the transition of mainly $1{t}_{2} or {t}_{1u}({\ensuremath{\sigma}}_{S})\ensuremath{\rightarrow}1s$. The manganates exhibit a simple $K{\ensuremath{\beta}}_{1,3}$ peak, while the manganese oxides show a pronounced $K{\ensuremath{\beta}}^{\ensuremath{'}}$ line. It is understood according to Tsutsumi's proposal on the origin of the $K{\ensuremath{\beta}}^{\ensuremath{'}}$ line.