Time-of-flight mass spectrometric studies on the plume dynamics of laser ablation of graphite

Abstract

Time-of-flight mass spectrometry has been used to probe neutral and positive ionic species produced by 266 nm laser ablation of graphite. At the laser fluence of 0.4–2.8 J/cm 2, C 3 was the major neutral species and C + and C 3 + were the major ionic species. The arrival time distribution of C 3 at 0.4 J/cm 2 was fitted with a thermal Maxwell-Boltzmann (MB) distribution. As the laser fluence was increased, a shifted MB distribution with a narrower width provided a better fit, indicating an influence of collisions of ablated species in the laser plume. For the arrival time distributions of C + and C 3 + at 0.9–1.3 J/cm 2, a shifted MB distribution with higher velocities than those of C 3 provided better fits. We discuss the expansion dynamics of the ablated species in the laser plume.