Multiwalled carbon nanotubes produced by direct current arc discharge in hydrogen gas

Multiwalled carbon nanotubes were produced by direct current (DC) arc discharge in the mixture gas of H-2-N-2. Raman scattering spectroscopy was used to characterize the MWNTs. Radial breathing mode vibration signals were observed at 272 and 388 cm(-1). Tangential mode vibration signal was observed at approximate to1582 cm(-1), and other intense signals were also observed at approximate to1860 cm(-1) for the MWNTs produced in the gas with the H-2 contents exceeding 90%. DC arc discharge in pure D-2 was also carried out, by which it was confirmed that the peak position and intensity of the Raman signal at approximate to1860 cm(-1) were independent of whether the gas was H-2 or D-2. This suggests that the 1860 cm(-1) band is not associated with hydrogen-based vibrations. (C) 2004 Elsevier B.V. All rights reserved.