Probing mesoscopic process of laser ablation in liquid by integrated method of optical beam deflection and time-resolved shadowgraphy
Probing mesoscopic process of laser ablation in liquid by integrated method of optical beam deflection and time-resolved shadowgraphy
复制标题
光束偏转与时间分辨阴影成像相结合的方法探测液体中激光烧蚀的细观过程
DOI：
10.1016/j.jcis.2016.09.032
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发表时间：
2017
影响因子：
9.9
通讯作者：
Haibo Zeng
中科院分区：
文献类型：
--
作者：
Jun Chen;Xiaoming Li;Yu Gu;Hao Wang;Xiufeng Song;Haibo Zeng
对于液体中激光烧蚀制备纳米材料，了解液体中激光与材料相互作用的介观过程是非常重要的。本文提出了一种结合时间分辨阴影法和光束偏转法的方法来研究纯水和含纳米颗粒（胶体）水的LAL过程。当激光聚焦到纯水中的靶上时，激光能量被靶吸收，产生等离子体、冲击波和气泡，沿着纳米颗粒的生成。而在胶体的情况下，激光束首先穿过溶液，与纳米颗粒相互作用，并在光路上诱导大量的零星阴影（小气泡），这些阴影被阴影照相术捕获。然后，激光到达靶并引起击穿，伴随着等离子体、冲击波和气泡的出现。同时，纳米粒子的浓度增加，纳米粒子的尺寸被修改。气泡的半径和振荡时间在胶体中比在纯水中小得多，这主要是由于纳米颗粒的破裂和在到达目标之前产生小气泡而导致的激光能量损失。此外，由于激光能量在到达靶点的过程中损失，气泡的最大半径和气泡振荡时间在初始阶段随激光照射次数的增加而迅速减小，然后达到一个稳定值。此外，我们使用烧蚀过程来解释纳米颗粒的双峰尺寸分布。这一工作将加深我们对液体中大块靶的激光烧蚀机理和液体中颗粒的激光辐照机理的理解。
For nanomaterial fabrication by laser ablation in liquid (LAL), it is very important to understand the mesoscopic process of laser interaction with materials in liquid. We proposed a method combining time-resolved shadowgraphy and optical beam deflection method to study the LAL process in both pure water and water with nanoparticles (colloids). As the laser was focused on the target in pure water, the laser energy was absorbed by the target and plasma, shockwaves and bubbles were produced, along with the generation of nanoparticles. While in case of colloid, laser beam first passed through the solution, interacted with nanoparticles and induced plenty of sporadic shadows (small bubbles) on the beam path which were captured by shadowgraphy. Then, the laser arrived at the target and induced breakdown accompanied by the emergence of plasma, shockwave and bubbles. Meanwhile, the concentration of nanoparticle increased and the sizes of nanoparticle were modified. The radius and oscillation time of bubbles are much smaller in the colloid than that in pure water, mainly due to laser energy loss by breakdown of the nanoparticles and generation of small bubbles before reaching the target. Moreover, we found the maximum bubble radius and bubble oscillation time decrease quickly with laser irradiation times at the beginning, and then reach a plateau, because of laser energy lost on the way to the target. In addition, we used the ablation process to explain a bimodal size distribution of nanoparticles. This work will deepen our understanding on the mechanism of both laser ablation of bulk targets in liquid and laser irradiation of particles in liquid.