Pulsed laser ablation of bulk target and particle products in liquid for nanomaterial fabrication

Abstract

Pulsed laser ablation in liquid (PLAL) is gradually becoming an attractive approach for nanomaterial fabrication because it is a chemically simple and clean method with high product purity. We studied the laser interaction with bulk target and particle products in detail, including mechanism process, target morphology and nanoparticle products. We captured three oscillations of one bubble after laser ablates the bulk target and calculated the variation of pressure and temperature inside the bubble. The results show that the first bubble oscillation has greatest impact on the nanomaterial synthesis, and the most powerful stages for the material synthesis during all the bubble oscillations are the beginning of each expansions and the end of each shrinks. Nanomaterial releases from the bubble at the end of each oscillations. In addition, based on the analysis of ablation cavity on the target, it is found that the cavity depth increases with the number of laser pulses, and then the depth tends to be under saturation status, which means it is difficult to obtain great improvement of the nanomaterial productivity just by prolonging the laser irradiation time. More importantly, the strong interaction between laser and particle products is presented clearly by time-resolved shadowgraphy, which can contributed to the modification of nanoparticle products.