Computer simulation study of damage and ablation of submicron particles from short-pulse laser irradiation

The dynamics of damage and ablation of individual particles of ;100 nm in size due to short-pulse laser irradiation is studied using a breathing sphere model and molecular dynamics simulations. The fluence thresholds for damage and ablation of irradiated particles have a strong pulse duration dependence. For 15 ps laser pulses, the laser induced pressure buildup and the focusing of the pressure wave in the center of irradiated particle leads to low thresholds for mechanical damage and ablation. The pressure driven particle disruption provides an effective mechanism for transfer of the laser energy into the energy of radial expansion of the ablation products. For 300 ps laser pulses, the explosive thermal decomposition of the particle is due to overheating and occurs at significantly higher laser fluences. Implications of the results of the simulations for the mass spectrometric aerosol characterization experiments and ablation of tissue in the case of inhomogeneous absorption of laser energy are discussed. q1998 Elsevier Science B.V.