Latent laser-induced graphitization of diamond

Basic features and mechanism of femtosecond laser graphitization of diamond surface were studied in the two regimes of irradiation: (1) by an intensive (>10 J/cm(2)) single shot and (2) by a train of pulses with near-threshold intensity (similar to 1-10 J/cm(2)). Special attention was paid to the so-called accumulative regime, when multipulse laser treatment results in prolonged delay of an appearance of crystal modification of the crystal. The light absorption mechanisms dominating in each regime are discussed. The experiments with fundamental (800 nm), second (400 nm) and third (266 nm) harmonics of Ti-sapphire laser (100 fs) have revealed that thermally stimulated processes play an essential role in latent diamond graphitization.