In the applications of single-walled carbon nanotubes (SWNTs), it is extremely important to separate semiconducting and metallic SWNTs. Although several methods have been reported for the separation, only low yields have been achieved at great expense. We show a separation method involving a dispersion-centrifugation process in a tetrahydrofuran solution of amine, which makes metallic SWNTs highly concentrated to 87% in a simple way.

We report here the structural determination of the Sc3C82 molecule by 13C NMR spectroscopy and X-ray single-crystal structure analysis. From the present study, it is obvious that the structure of Sc3C82 is not Sc3@C82 but Sc3C2@C80.