Direct manganese (Mn) speciation in solid state materials by pulsed glow discharge time-of-flight mass spectrometry

Abstract

Accurate quantification of specific oxidation states of elements present in complex, solid state samples can be difficult because extraction procedures often lead to changes in those oxidation states. Direct approaches to speciation for solid state materials preclude the extraction step and thus enable more accurate quantification of different oxidation states present in the original material. In this work, pulsed glow discharge time-of-flight mass spectrometry provides such direct differentiation between manganese (IV) dioxide and manganese (II) monoxide in a solid state sample. The spatial and temporal characteristics of the glow discharge source are evaluated and optimized for such speciation by careful control of operating parameters, such as supporting gas pressure, operating power, and temporal observation window. Conditions are found that favor the production of the cluster ion, Mn₂O₃⁺, characteristic for manganese (IV) dioxide. It is demonstrated here that once this has been accomplished, the two oxides can be differentiated and quantified.