Spectroscopic studies of functionalized fullerenes and carbon nanotubes

Strong luminescence emission over a broad wavelength region was detected from well-dispersed functionalized carbon nanotubes. The better dispersion and functionalization of the nanotubes resulted in more intense luminescence emissions. This emission may be attributed to the trapping of excitation energy by defect sites in the nanotube structure, which are passivated upon the appropriate functionalization of the nanotubes. Better functionalization improves not only the nanotube dispersion but also the surface passivation to make the energy trapping sites more emissive, leading to stronger luminescence emissions.; Luminescence anisotropy of well-functionalized single-wall (SWNT) and multiple-wall (MWNT) carbon nanotubes in solution and in a polymeric thin-film matrix was investigated for their defect-derived luminescence properties. Strong luminescence polarization for the functionalized carbon nanotubes in solution and film were observed with anisotropy values approaching the limit for collinear absorption and emission dipole moments in the film; the partial depolarization in solution is rationalized in terms of the flexibility of the nanotubes. Mechanistic implications of the polarization spectroscopy results for the luminescent functionalized nanotubes in the polymeric matrix with and without the mechanic alignment are inferred.; Visible luminescence emission with high sensitivity to bundling effects may prove valuable in the evaluation of dispersion in functionalized carbon nanotube samples and related nanocomposite materials. Single-walled carbon nanotubes were functionalized with amino-terminated polyimide specially designed to be structurally identical to the polymer matrix to ensure compatibility. The nanotube dispersion state in nanocomposites embedded with covalently functionalized nanotubes were systematically evaluated through spectroscopic and microscopic techniques by directly comparing to nanocomposites embedded with non-functionalized nanotubes at the same loading of nanotube equivalent. The results proved that nanotubes with covalently functionalized polymeric groups were of improved nanotube dispersion. The spectroscopic evidence may be applied as direct measurement of nanotube dispersion.; The charge transfer properties of methano-fullerene adducts of multiple electron donors D2 and D12 were systematically studied compared with their reference compounds R2 and R 12. The spatial configuration of the electron donors and the acceptor in these fullerene-based redox systems represents a crucial factor in determining the electron transfer activities and the formation of charge transfer complexes.