Carbon nanotubular structures synthesis by means of ultraviolet laser ablation

We report on the synthesis of carbon nanotubular structures produced for the first time by means of pulsed KrF laser ablation of a graphite pellet at high temperature (1150 °C), under high argon gas pressure (500 torr), and at relatively high ultraviolet (UV) laser intensities (8 × 10⁸ W/cm²). The carbon nanotubular structures were directly observed by transmission electron microscopy and characterized by micro-Raman spectroscopy. Nanohorns (∼2.5 nm diameter and ∼10 nm long), a few single-wall nanotubes (1.2 to 1.5 nm diameter), and other nanotubular structures (such as graphitic nanocages and low-aspect-ratio nanotubules) were clearly observed in the carbon deposit. Raman spectra in the low-frequency range confirmed a population of tubular structures with diameters ranging from 0.7 to 2.0 nm. It is shown that the relatively high UV laser intensity used here favors the growth of various nanotubular structures to the detriment of single-wall nanotubes.