Laser-induced graphitization on a diamond (111) surface

We report an atomistic simulation study of laser-induced graphitization on the diamond (111) surface. Our simulation results show that the diamond to graphite transition occurs along different pathways depending on the length of the laser pulse being used. Under nanosecond or longer laser pulses, gr aphitization propagates vertically into bulk layers, leading to the formati on of diamond-graphite interfaces after the laser treatment. By contrast, w ith femtosecond (0.2-0.5 ps) laser pulses, graphitization of the surface oc curs layer by layer, resulting in a clean diamond surface after the ablatio n. This atomistic picture provides an explanation of recent experimental ob servations.