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.
Highlights
Laser has been widely used in the field of information communication, medical treatment, industry and military, since Maiman constructed the first functional laser in 1960.1 Among which the laser-assisted fabrication of nanocrystals and functional nanostructures has received great attention over the last decade
The nanoparticle products are characterized by x-ray diffraction (XRD) and transmission electron microscope (TEM), and the dependence of the nanoparticle distribution on the laser ablation of particle products is discussed
The most powerful stages during all the bubble oscillations are the beginning of each expansions and the end of each shrinks for the material synthesis
Summary
Laser has been widely used in the field of information communication, medical treatment, industry and military, since Maiman constructed the first functional laser in 1960.1 Among which the laser-assisted fabrication of nanocrystals and functional nanostructures has received great attention over the last decade. It is trend to study the mesoscopic process of laser ablation in liquid for nanomaterial synthesis in order to improve the properties and the controllability of products. Jun Chen et al use a method combining time-resolved shadowgraphy and optical beam deflection method to study the PLAL process and explain a bimodal size distribution of nanoparticles based on the ablation mechanism.. Jun Chen et al use a method combining time-resolved shadowgraphy and optical beam deflection method to study the PLAL process and explain a bimodal size distribution of nanoparticles based on the ablation mechanism.14 They propose an approach based on dual laser beam ablation for nanomaterial synthesis and show that dual laser-induced bubble dimer promotes the agglomeration of two kinds of metal particles. For the nanosecond laser which used most commonly, it is found that the cavitation bubble dynamics is one of the main stages involved in PLAL process, which plays scitation.org/journal/adv an important role in nanoparticle formation. Julien Lam et al examine the initial growth and collapse stages of bubbles induced by laser ablation in liquids and give an insight about the chemical composition and the thermodynamic properties within the bubble. Stefan Reich et al use visible-light stroboscopic imaging and x-ray radiography to study the interaction between bubble and nanoparticles, and show that the bubble motion acts on the particle distribution as confinement and retraction force to create secondary agglomerates. Jun Chen et al use a method combining time-resolved shadowgraphy and optical beam deflection method to study the PLAL process and explain a bimodal size distribution of nanoparticles based on the ablation mechanism. They propose an approach based on dual laser beam ablation for nanomaterial synthesis and show that dual laser-induced bubble dimer promotes the agglomeration of two kinds of metal particles.
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