Distinguishing between High- and Low-Spin States for Divalent Mn in Mn-Based Prussian Blue Analogue by High-Resolution Soft X-ray Emission Spectroscopy

We combine Mn L-2,L-3-edge X-ray absorption, high resolution Mn 2p-3d-2p resonant X-ray emission, and configuration interaction full-multiplet (CIFM) calculation to analyze the electronic structure of Mn-based Prussian blue analogue. We clarified the Mn 3d energy diagram for the Mn2+ low-spin state separately from that of the Mn2+ high-spin state by tuning the excitation energy for the X-ray emission measurement. The obtained X-ray emission spectra are generally reproduced by the CIFM calculation for the Mn2+ low spin state having a stronger ligand-to-metal charge-transfer effect between Mn t(2g) and CN pi orbitals than the Mn2+ high spin state. The d- d-excitation peak nearest to the elastic scattering was ascribed to the Mn2+ IS state by the CIFM calculation, indicating that the Mn2+ LS state with a hole on the t(2g) orbital locates near the Fermi level.