Optical microspectroscopy study on enriched (11,10) SWCNTs encapsulating C60 fullerene molecules

The interaction between C60 fullerene molecules and single-chirality (11,10) single-walled carbon nanotubes (SWCNTs) is demonstrated by probing the optical transitions in (11,10) peapods by optical microspectroscopy. The results of the (11,10) SWCNTs and (11,10) peapods are compared to multi-chirality SWCNTs and peapods. The absence of the fine structure of the absorption bands in the case of (11,10) SWCNTs in comparison to multi-chirality SWCNTs demonstrates that the (11,10) SWCNTs provide a well-defined environment for studying the interaction between the encapsulated C60 molecules and the nanotubes. As compared to (11,10) SWCNTs, the absorption bands in (11,10) peapods show a large red shift and a reduction of the spectral weight. These findings suggest that the filling of the (11,10) SWCNTs with C60 molecules increases the internal dielectric constant and induces a charge transfer between the SWCNTs and the encapsulated C60 molecules. For testing the effect of the internal dielectric constant and charge transfer on the optical properties of the (11,10) SWCNTs, the (11,10) peapods were transformed to double-walled carbon nanotubes (DWCNTs) using the laser irradiation method. The transformation of the encapsulated fullerene molecules into inner wall reduces the environmental dielectric constant as well as the charge transfer from the outer tube.