Formation of carbon-nanostructure from X-ray induced defect in single-walled carbon nanotubes2016 · 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.
Origin of a Raman scattering peak generated in single-walled carbon nanotubes by X-ray irradiation and subsequent thermal annealing2016 · We have found that a Raman scattering (RS) peak around 1870 cm(-1) was produced by the annealing of the X-ray irradiated film of single-walled carbon nanotubes (SWNTs) at 450 degrees C. The intensity of 1870-cm(-1) peak showed a maximum at the probe energy of 2.3 eV for the RS spectroscopy with various probe lasers. Both the peak position and the probe-energy dependence were almost identical to those of the one-dimensional carbon chains previously reported in multi-walled carbon nanotubes. Consequently, we concluded that the 1870-cm(-1) peak found in the present study is attributed to carbon chains. The formation of carbon chains by the annealing at temperature lower than 500 degrees C is firstly reported by the present study. The carbon chains would be formed by aggregation of the interstitial carbons, which are formed as a counterpart of carbon vacancies by X-ray irradiation diffused on SWNT walls. The result indicates that the combination of X-ray irradiation and subsequent thermal annealing is a feasible tool for generating new nanostructures in SWNT. (C) 2016 Author(s).