Highly Resolved Mn Kβ Emission: A Potential Probe in Laboratory for Analysis of Ligand Coordination around Mn Atoms in Gels and Solutions.

Mn Kβ spectra of Mn, MnO, MnSO·HO, KMnO, 0.50 M MnSO aqueous solution, and the precipitation bands of Mn-Fe-based Prussian blue analogs formed in 2.4 wt.% agarose gel ("Gel") were measured using a laboratory-use X-ray setup with ∼2.6 eV instrumental resolution, which comprises a cylindrically bent Si (400) crystal monochromator and a spherically bent Ge (440) crystal analyzer. The oxidation-state dependent shift of the Mn Kβ peak (∼1 eV) was clearly observed for Mn, MnO, and KMnO, confirming that the employed setup can acquire the key features of Mn Kβ spectra. The Mn Kβ spectra of MnSO·HO, the 0.50 M solution, and Gel exhibited small but distinguishable differences, whereas the spectra acquired at two positions in Gel were almost the same. These results suggest that highly resolved Mn Kβ spectra can be helpful for assessing ligand coordination around Mn atoms in gels and solutions.