The mechanisms of nickel thin films irradiated by femtosecond laser pulse trains are studied by a model using molecular dynamics simulations and two-temperature model. It is found that the pulse train technology can change energy transport and corresponding phase change processes. Compared with single pulse ablation at the same total fluence, the pulse trains lead to (1) lower ablation rate with more and smaller uniform nanoparticles, (2) higher film surface temperatures and longer thermalization time, (3) much lower electron thermal conductivity that can further control heat-affected zone, (4) significantly smaller film compressive stresses and tensile stresses which reduce microcracks, and (5) a transition from phase explosion to the critical point phase separation which favors small uniform nanoparticle generation.
X. Li et al., "Phase Change Mechanisms During Femtosecond Laser Pulse Train Ablation of Nickel Thin Films," Journal of Applied Physics, American Institute of Physics (AIP), Sep 2009.
The definitive version is available at http://dx.doi.org/10.1063/1.3223331
Mechanical and Aerospace Engineering
Ministry of Science and Technology of the People's Republic of China. 111 Project
Ministry of Science and Technology of the People's Republic of China. 863 Program
China Postdoctoral Science Foundation
National Natural Science Foundation (China)
Keywords and Phrases
Compressive Strength; High-Speed Optical Techniques; Metallic Thin Films; Microcracks; Molecular Dynamics Method; Phase Change Materials; Phase Separation; Tensile Strength; Nanoparticles; Nickel; Thermal conductivity
Article - Journal
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