Formation of carbon-nanostructure from X-ray induced defect in single-walled carbon nanotubes

We have studied annealing effects on X-ray irradiated single-walled carbon nanotubes (SWNTs) by confocal micro-Raman scattering spectroscopy. The SWNT films irradiated with 1254-eV X-ray were annealed in argon atmosphere with increasing the temperature from 200 degrees C to 500 degrees C by 100 degrees C. We found that a new Raman peak at similar to 1130 cm(-1) came into existence after the annealing at 300-400 degrees C. The 1130-cm(-1) peak was grown by the annealing exclusively in the X-ray irradiated sample. It is presumable that the 1130-cm(-1) peak is ascribed to carbon nanostructure formed by the annealing of the X-ray irradiated SWNT. Based on the comparison of spatial images of Raman intensity, the nanostructure responsible to the 1130-cm(-1) peak is likely formed by aggregation of interstitial carbon atoms diffused on SWNT surface. Because of the comparison of the probe wavelength dependence of the peak frequency with previous reports, we concluded that polyacetylene-like structures are formed by the post-irradiation annealing of SWNT. (C) 2016 Elsevier B.V. All rights reserved.