(a) Electric force microscopy (EFM) image of the same SWNT serpentine discussed in Figure 6. (b) Scanning across the SWNT, the cantilever frequency shift is different if a tube is semiconducting (“W shaped” blue line) or metallic (“V shaped” red line) [57]. The red and blue lines in (a) indicate the two regions where these profiles in (b) were acquired [30].
