Potassium ferrioxalate has been used as chemical actinometer, and the experimental procedure was based on literature. The potassium ferrioxalate was either directly used from the supplier (Alfa Aesar) or made by mixing iron(III)chloride (Sigma Aldrich) with di-potassium oxalate (Sigma Aldrich) in a 1:3 mole ratio. The product was obtained by crystallization, which was performed two times, whereafter the crystals were placed in a desiccator to dry.