Formation and Raman spectroscopy of single wall carbon nanotubes synthesized by CO2 continuous laser vaporization

Single wall carbon nanotubes of tubule diameter 1.0-1.7 nm were synthesized by the irradiation of continuous CO2 laser (500-900 W) onto a graphite-Co/Ni composite target at room temperature. We suggest that the high temperature plays a unique key role in the growth of single-wall carbon nanotubes in the laser ablation method, while laser wavelength is less important. The transmission electron microscope observations show that the average diameter of single wall carbon nanotubes produced by the CO2 laser is larger than one produced by YAG laser vaporization, and the tube diameter increases with increasing laser power. We present the Raman spectrum of single-wall carbon nanotubes produced by using CO2 continuous laser vaporization with laser excitation wavelengths 632.8 and 514.5 nm, and these Raman scattering are compared with those of nanotubes produced by other laser ablation of previous reports.