During the EMAS measurement, the modulated potential component was applied to the sample in such a way, that the total potential signal always oscillated between OCP and a corresponding reductive or oxidative potential. At the beginning of the measurement, the peak-to-peak amplitude was 60 mV. With an appropriate offset, the signal is then shifted to positive or negative values, so that the potential then modulated between OCP and OCP ±60 mV. At this potential, a complete spectrum from 350 to 860 nm was scanned in 3 nm steps. Afterwards, the peak-to-peak amplitude was increased by 60 mV, the signal offset was adjusted accordingly, and a complete spectrum was recorded again. This was done until the final corresponding oxidative or reductive potential was reached and a complete data set was recorded.