Selective formation of C20 cluster ions by field evaporation from carbon nanotubes

Carbon cluster ions generated by field evaporation from single-walled nanotubes and multi-walled nanotubes have been analyzed by mass spectrometry. The observed mass spectra showed that the singly charged C-20 clusters, C-20(+), were selectively generated as magic clusters for both SWNTs and MWNTs. The onset evaporation field of C-20(+) was estimated to be about 10 V nm(-1). The specific number of atoms comprising the magic cluster indicates a dodecahedral structure instead of a linear chain or a ring. (C) 1999 Elsevier Science B.V. All rights reserved.