Dynamics of femtosecond laser produced tungsten nanoparticle plumes

We investigated the expansion features of femtosecond laser generated tungsten nanoparticle plumes in vacuum. Fast gated images showed distinct two components expansion features, viz., plasma and nanoparticle plumes, separated by time of appearance. The persistence of plasma and nanoparticle plumes are similar to 500 ns and similar to 100 mu s, respectively, and propagating with velocities differed by 25 times. The estimated temperature of the nanoparticles showed a decreasing trend with increasing time and space. Compared to low-Z materials (e. g., Si), ultrafast laser ablation of high-Z materials like W provides significantly higher nanoparticle yield. A comparison between the nanoparticle plumes generated by W and Si is also discussed along with other metals. (C) 2013 AIP Publishing LLC.