Photoluminescence of multiwalled carbon nanotubes excited at different wavelengths

In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron \pi in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.