Summary:
When the lateral displacement of the tip (see Fig.1) is comparable or larger than the scan area size, for example at atomic-scale friction, the interpretation of friction image is changed from the case that the scan size is much larger than the lateral displacement of the tip. The same situation occurs in contact mode surface corrugation measurement. This is because, by the lateral displacement of the tip, the tip is not at the position where the raster scan points, which is clearly observed by an in-situ TEM/AFM combined microscopy and atomic-scale friction analysis by two-dimensional stick-slip model. Moreover, the lateral displacement of the tip, i.e. friction at the order of nm scale creates the hysteresis in the force-distance relation curve behavior, as shown in Fig.2.

Fig.1: Lateral displacement along Y direction is generated by the Z direction force. This means that the AFM tip slides along surface during force-distance curve!		Fig.2: A typical force-distance relation curve of AFM shows the hysteresis, which is caused by the lateral displacement of the tip.

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