Fig. 3
From: Rate-selected growth of ultrapure semiconducting carbon nanotube arrays
Bandgap dependent dimer addition process. a Minimum bandgap (target layer) of concentric layers for few-walled CNTs versus TOF of the target layer. Detection of 12C preceded 13C signal verified the expected tip mode, also indicated by the AFM image on the tip of a long CNT (inset, scale bar, 10 nm). The errors come from the uncertainty of identifying the transition site. b Diameter distribution of CNTs longer than 154 mm. This reveals a trend that DWNTs are highly enriched (75%) among long species with the diameter smaller than 3 nm, whereas TWNTs dominate for tube diameter larger than 3.5 nm. c Schematic of the TOF differences between m- and s-CNTs. After adding each dimer, both the m- and s-CNT will survive or die, with equal α but different dimer-addition frequencies, which results in differences between αm and αs. This enables a spontaneous purification of s-CNTs from their m-counterparts
