Comprehensive spectroscopic study of nitrogenated carbon nanotubes

Carbon nanotubes with different nitrogen contents were produced by the arc-discharge technique. The samples were first submitted to a concentration process (purification) and analyzed by x-ray photoelectron spectroscopy, electron-energy-loss spectroscopy, electron transmission, and scanning electron microscopy to study the materials structure and morphology. Measured values of nitrogen concentration were below 5 at. % and varied with the nitrogen partial pressure inside the arc-discharge chamber. Using an optical microscope, highly localized regions of the samples (similar to1 mm(2)) were irradiated by an Ar ion laser. Controlling the laser intensity, further local purification was induced and information about the evolution of the structural order of the nanotube samples with different contents of nitrogen was obtained.