Spectrum acquired above the centre of an isolated pentacene molecule (Vd.c. = 1.76 V, Va.c. = 1.00 V, A = 1 Å, 0→1−). Δz is given with respect to an AFM setpoint of Δf = −3.2 Hz at Vd.c. = 0 V. Signal saturation is observed at short tip–sample distances because not more than one electron per set pulse can be transferred.