Diameter selective doping of single wall carbon nanotubes

Single wall carbon nanotubes (SWCNTs) synthesized by the recently developed HiPco(R) method differ from those obtained by other techniques because their diameter distribution is broader and is centered at a smaller value. Therefore, HiPco(R) samples contain an unusual wide selection of different nanotubes. Combining this feature with different dopant molecule sizes makes it possible to study a special, diameter selective intercalation phenomenon. Here we present a comparative resonant Raman spectroscopic study on the n-type (K) and p-type (FeCl3) doping of a HiPco(R) and a laser ablation grown SWCNT sample. Diameter selectivity is observed in the former but not in the latter case. We suggest that the solvability of dopands is diameter dependent with a minimum in the range d = 0.9-1.2 nm.