Carbon rings and cages in the growth of single-walled carbon nanotubes

We present a growth model for single-walled carbon nanotubes (SWNTs) based on experimental observation and energetic considerations. Carbon rings, obs erved experimentally and suggested to be fullerene precursors, are the temp lates for SWNTs nucleation. SWNTs grow by addition of C-2 radicals to catal ytically induced reactive sites. This model is consistent with known experi mental results and explains the characteristic diameter distribution of SWN Ts as resulting from the gas-phase distribution of carbon ring isomers. (C) 2000 American Institute of Physics. [S0021-9606(00)71333-X].