Phonon Control In Metallic Carbon Nanotubes Due To Laser-Induced Defects

Single-walled carbon nanotubes (SWNTs) irradiated with laser were investigated by Raman spectroscopy. The intensity of D band related to defects increased with the laser irradiation. It should be noticed that the corresponding change was observed for G-peak associated with metallic SWNTs that is related to the electron-phonon coupling with Kohn anomaly. The upshift and narrowing of the G-peak occur due to the laser irradiation. The G-peak can recover the original one due to the thermal annealing. On the other hand, G band associated with semiconducting SWNTs remained unchanged even after the laser irradiation. This means that the laser-induced defects significantly affect phonons in metallic SWNTs, compared with Semiconducting ones, and can control the electron-phonon coupling. (C) 2008 American Institute of Physics.