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_2,3-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 π orbitals than the Mn²⁺ high spin state. The d - d-excitation peak nearest to the elastic scattering was ascribed to the Mn²⁺ LS state by the CIFM calculation, indicating that the Mn²⁺ LS state with a hole on the t_2g orbital locates near the Fermi level. (Chemical Equation Presented).