A multi wavelength Raman scattering study of defective graphitic carbon materials: The first order Raman spectra revisited

The Raman spectra of a number of defected graphitic carbonaceous materials have been recorded using a large panel of laser exciting lines ranging from 1064 to 325 nm. They concern Arkema and Nanocyl multiwall nanotubes, Pyrograph nano filaments, heat-treated glassy carbons and graphite nano platelets. A particular attention was paid on the characteristic spectral range (approximate to 1000-1300 cm(-1)) of the so-called D-4 band. It is shown that in fact three different components participate to the scattered signal in this spectral range, whose relative intensities depend on the carbon considered. They include the dispersive D '' band, an additional dispersive band denoted D** and a non-dispersive band denoted D*. When considering the different defect-induced double resonance inter-valley scattering processes, and according to symmetry considerations, these components are assigned to phonon modes belonging to different dispersion branches away from the K point of the Brillouin zone in the Gamma-K direction (D ''), in the K-M direction (D**) and in the very close vicinity of the K point (D*). (C) 2016 Elsevier Ltd. All rights reserved.