A soft XAS transmission cell for operando studies.

A new cell for operando soft X-ray absorption spectroscopy in transmission mode is presented. Developed for investigations on solar water-splitting catalysts, the cell allows the study of solid films in direct contact with electrolyte solution while applying voltage and visible light. The design is optimized for fast sample exchange and the simultaneous measurement of fluorescence and transmission signal. The capability of the cell is presented on a manganese oxide (MnO) film, where electronic structure changes are monitored during forward and backward potential changes. Detailed information about the varying contributions of several Mn oxidation states during this process was revealed.