FT-ICR Study of Precursor Clusters of Single Wall Carbon Nanotubes (SWNTs)

Metal-carbon binary clusters generated by the laser vaporization of Ni/Co and Ni/Y doped graphite samples used for the macroscopic laser-oven production of SWNTs were studied. Positive and negative clusters generated by the laser-vaporization supersonic-expansion cluster beam source were directly injected to the FT-ICR (Fourier Transform Ion Cyclotron Resonance) mass spectrometer. Depending on the metal species, the generation efficiency of metal-carbon binary clusters was drastically different. The chemical reaction of these clusters with NO gas was used as the probe of the geometrical structure of clusters. The reactivity to NO of these binary clusters was completely different. In case of YC n (n = even, n • † 36), chemical reaction of YC n with NO was not observed while pure carbon clusters were reacted. On the other hand, for MC n (M = Ni or Co), the reactivity was much higher than pure carbon clusters. It was speculated that a few Ni or Co atoms attached outside of imperfect carbon cage for Ni/Co doped case, and that Y atom was included in the carbon cage for Ni/Y doped case.