Fig. 2.

CNT architectures showing four-generation Y-branching. (A) Drawing (Right) shows the structure of the typical four-generation Y-branched nanotube. (Left) The four parallel interfaces (marked with white arrows) in the low-magnification SEM image show the locations where the four generations of Y-branching take place, respectively. (B-E) The high-magnification image from each interface clearly reveals the corresponding Y-branches and the decreasing diameters of the branched nanotube segments, showing the first (B), second (C), third (D), and fourth (E) Y generations. The Y-junction is contoured in white lines for clarity. Insets at top right show schematics of the whole architecture with the specific junction highlighted in white. (Scale bars: 100 nm.)