Molecular dynamics simulation of the laser disintegration of aerosol particles

The mechanisms of disintegration of submicrometer particles irradiated by s hort laser pulses are studied by a molecular dynamics simulation technique. Simulations at different laser fluences are performed for particles with h omogeneous composition and particles with transparent inclusions. Spatially nonuniform deposition of laser energy is found to play a major role in def ining the character and the extent of disintegration. The processes that co ntribute to the disintegration include overheating and explosive decomposit ion of the illuminated side of the particle, spallation of the backside of large particles, and disruption of the transparent inclusion caused by the relaxation of the laser-induced pressure. The observed mechanisms are relat ed to the nature of the disintegration products and implications of the sim ulation results for aerosol time-of-flight mass spectrometry are discussed. Application of multiple laser pulses is predicted to be advantageous for e fficient mass spectrometry sampling of aerosols with a large size to laser penetration depth ratio.