Atomic size-limited intercalation into single wall carbon nanotubes

Intercalation of single wall carbon nanotubes ( SWNTs) provides an important tool to modify their electronic band structure. Using multiple excitation wavelength Raman spectroscopy, we demonstrate that intercalation into SWNT interiors can be limited by intercalant size resulting in an unusual material comprising SWNTs with varying charge density. In the particular case of iodine intercalation, larger SWNTs with iodine- filled interiors were found to carry significantly higher charge density as compared to smaller empty ones. This difference was used to separate the intercalated SWNT material into fractions with homogeneous charge density.