Laser-Induced High Local Temperature in Carbon Nanotube

Laser irradiated carbon nanotubes in vacuum can emit dazzling yellow light due to the laser heating effect. We investigated the phonon frequency shifts of as irradiated carbon nanotube bundles by Raman spectroscopy under ultraviolet laser illumination (325 nm, 2.4 mW), the G band peak position was found to shift 50 cm-1 to lower wave number. By considering the temperature coefficient of the G band shift, the local temperature of the illuminated spot was predicted to be nearly 2000K. This temperature had a linear relationship with the incident laser power, and also was greatly influenced by the pressure of the vacuum chamber. The photoluminescence of the CNT bundle was also studied, which exhibits an oscillation of 0.1 eV, a possible origin of the oscillation was discussed.