Pulsed laser ablation of graphite in O2 atmosphere for preparation of diamond films and carbon nanotubes

Abstract

Spatially and time-resolved optical emission analysis was carried out for the plasma plume produced by KrF excimer laser ablation of graphite in various oxygen atmospheres. Furthermore, highly ordered carbon nanofibers were fabricated by pulsed laser ablation using a graphite target containing approximately 1 mol.% metal oxide, such as NiO. In our laser ablation process, carbon nanofibers are deposited in an oxygen atmosphere. From the optical emission study, the visible carbon plasma plume in O2 gas was found to be dominated by the emission of C2 molecules and C atoms. Emission of a C2 Swan band was strongly observed near the substrate under the diamond growth conditions (0.1–0.15 torr O2). From the time-resolved emission study, ablated carbon particles were estimated to have a high kinetic energy of approximately 10 eV.