Direct determination of Mn valence states in mixed‐valent manganates by photoluminescence spectroscopy

Mn‐based materials are excellent catalysts with applications in many complex heterogeneous charge transfer processes because of their ability to exist in several stable oxidation states. However, accurate detection of Mn valence states is challenging due to the limitations of X‐ray‐based spectroscopic techniques to successfully resolve individual oxidation states. In this work, we performed a combined photoluminescence (PL) and X‐ray photoelectron spectroscopy (XPS) analysis of many Mn compounds to show that PL spectroscopy can consistently detect Mn in different oxidation states and their composition can be determined through a simple fitting procedure. The results suggest that PL spectroscopy can be a relatively simpler, benchtop alternative to X‐ray based techniques for direct metal cation detection without the need for multiplet fitting analysis.