We further test our hypothesis that it is the measurement time and limited stability of the QDs in the electrolyte solution which causes the induced absorption for reductive scans. To this end, we freshly prepare four samples of PbS-A and measure each one 25 times at the same individual potential (~30 min per measurement). At -0.48 V, e.g. close to the measured OCP, no features are visible (Figure ). We emphasize that the total duration of this measurement is >12 h, and from Figure , one would expect to see a significant increase in background absorption. We argue that the lock-in technique used here prevents the registration of such an erroneous signal: EMAS amplifies exclusively such signals that oscillate with the locked-in frequency. Because the increased background absorption is independent of the applied potential, it does not oscillate with the locked-in frequency, and it remains invisible in Figure .