Atomic-scale damage mechanism of diamond during laser processing

Laser processing is widely used for diamond machining, yet its atomic-scale damage mechanisms remain unclear due to the complex interactions between laser and diamond. In this work, femtosecond laser experiments and molecular dynamics (MD) simulations were combined to elucidate the atomic-scale damage mechanisms of diamond during laser processing. Laser experiments reveal that multi-pulse irradiation leads to deep ablation crater, while single-pulse laser irradiation induces surface bulging, with damage characteristics strongly dependent on the energy density. The detailed analysis of the surface morphologies and subsurface structures were provided, identifying distinct bulging–swelling–melting and recasting–laser induced periodic surface structure (LIPSS) formation pathways linked to energy density. Complementary MD simulations resolve the transient evolution of temperature, stress fields, and local bonding configurations, reproducing the experimental observations and uncovering a coupled thermo-stress-phase transition mechanism that drives the structural transformation of diamond. Notably, crystal orientation is found to play a crucial role in modulating the damage propagation and material removal mechanisms. The (111) crystal plane exhibits unique atomic-layer exfoliation, while the (100) and (110) planes show more rapid stress expansion and surface deformation. The study establishes a mechanistic map linking energy density, crystal orientation, and damage mode and offers critical insights for tailoring laser parameters during laser processing of diamond.