Identification by laser desorption ionization mass spectroscopy of large fullerenes formed during the growth of single-walled carbon nanotubes in the HiPco process

Abstract

Iron catalyzed gas-phased disproportionation of carbon monoxide under high pressure is known to produce carbon Single Walled Nano-Tubes (SWNT). Non-tubular carbon by products and iron encapsulated-graphitic shelled nano-particles are produced concomitantly under conditions optimized for SWNT production, are undesirable bi-products. Differences in oxidation thresholds of the constituents and acid leaching of iron particles have been exploited in the co-development of Laser Desorption Ionization Mass Spectroscopy (LDI) evaluation and SWNT purification. LDI threshold conditions have been established for the analysis of non-SWNT carbon species. It has been shown that neither photochemical decomposition nor photo assisted molecular self-assembly contribute to the mass spectra. Raw, processed materials and molecular specific extractions are evaluated. Laser Desorption Ionization mass spectroscopy, Transmission Electron Microscopy, Raman and TGA results are reported