In this paper, Molecular Dynamics (MD) simulations are conducted to study the dynamic process of nanoparticle formation in picosecond laser materials interaction. It is found that nanoparticles originate from an intense vapor phase explosion process driven by an accumulated high pressure in the near surface region. The pressure in nanoparticles undergoes a reduction process as a result of temperature decay and atom re-construction in space. The velocities of particles in the x and y directions are much smaller than that in the z direction and do not change much with the laser fluence. The average velocity in the z direction for monomers and dimers increases continuously with the increasing laser fluence. For larger particles, their velocity in the z direction first increases with the increasing laser fluence, then is saturated. When the laser fluence increases, the total momentum of particles in the z direction increases almost linearly with the laser fluence. Saturation of the nanoparticle (large ones) yield is observed when the laser fluence reaches a certain level, which is a consequence of limited heat penetration depth during laser heating. For monomers and small particles, it is observed that their yields increase almost linearly with the increasing laser fluence.
Back to Sub-wavelength Nanostructuring II
Back to SES Abstracts
Back to The 41st Annual SES Technical Meeting