Artifact E, as shown on the left of Fig. 7, is the result of feedback oscillation when the leftward foot of the J-tip is in contact with left tip corners of the grating. In normal operation, that part of the profile should have a rounded shape. More difficulty occurs in artifact F where the tip going down the sidewall begins to flex/buckle, and the cantilever keeps going, producing the apparent trenches (false height contrast), until the CNT relaxes to its undistorted shape at the point G. In the retrace, there are large feedback oscillations, artifact H, shown in the right of Fig. 7. These occur when the tip is scanning down the sidewalls, and it is expected that the vertical portion of the CNT is in contact with the sidewall as a whole. Additionally, the artifacts B and C that were observed using the B-tips (Fig. 5) are also apparent in the J-tip profiles shown in Fig. 7.