We have developed a novel method for the purification of single-wall carbon nanotubes (SWNTs) that involves annealing in air and dispersing the SWNTs in an aqueous solution of carboxymethylcellulose (CMC). The purity of the resulting SWNTs was evaluated by analytical techniques such as electron microscopy, Raman spectroscopy, and thermogravimetric analysis (TGA). As a result, it was revealed that CMC functioned as an effective dispersion reagent in the exfoliation of the SWNT bundles and thereby, SWNTs with appreciably high quality were prepared.

The isolation of single-wall carbon nanotube (SWNT) bundles and purification of these SWNTs were investigated by dispersing the SWNTs in an aqueous gelatin solution. TEM images of the SWNTs dispersed in the gelatin solution showed that the interaction between the gelatin molecules and the SWNTs produces a transformation of the SWNT bundles into thin bundles. Raman spectra measurements revealed that dispersing the SWNTs in the gelatin solution is a good purification procedure for the SWNTs.

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We have developed a simple procedure for the purification of single wall carbon nanotubes (SWNTs) with gelatin as the dispersing reagent. The steps of this procedure were performed in the following order: annealing in air, sonication in an aqueous solution of gelatin, and soaking in hydrochloric acid solution. The advantage of using gelatin as a dispersing reagent is not only that it is useful for untangling the SWNT bundles, but also that the gelatin molecule and the metallic catalyst can be removed using HCl.

The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photoninduced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si − and Cl − , fragments and excited neutral atomic, Si * , fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.