Figure 4

Surface potential shifts after electrostatic charging for positive and negative polarity. The data points correspond to average potential within the individual stripes that were charged using (a) ±20 V or (b) ±25 V. Positive and negative data points at the same x-value were obtained from a charging experiment and KFM in one scan frame. Only in the case of x = 4 in (b) the patterns were charged in separate frames. The x-axis values between two integer values in (a) correspond to experiments conducted within the same day.