Pulsed laser ablation in liquid (LAL) is a method for synthesizing nanoparticles with controlled composition and high purity. However, current research predominantly examines isolated cavitation bubbles, overlooking real-world LAL scenarios where numerous bubbles interact simultaneously. This study addresses this gap by investigating the effects of short-range micrometric spatially controlled double-pulse laser ablation in liquids on nanoparticle size distribution. Gold and YAG are used as model materials, and a dimensionless parameter, H*, is introduced to quantify the ratio between double bubble spatial separation and their maximum height. This parameter correlates with cavitation bubble merging time, bubble volume change rate, and subsequent nanoparticle size increase. Shadowgraphs provide valuable insights into bubble contact and fusion dynamics, showcasing phase separation by a thin water film and subsequent merging into a single bubble. Notably, a twofold increase in nanoparticle size is observed for both Au and YAG at H* = 0.25. The research indicates a strong association between nanoparticle size trends and cavitation bubble volume rate change, particularly emphasized at H* = 0.25. Understanding the dynamics of neighboring bubbles during LAL emphasizes the relevance of lateral pulse distances in dual-beam LAL, impacting particle size distribution in a distance-dependent manner.

中文翻译：

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液体中短程空间控制双束激光烧蚀如何控制纳米颗粒尺寸和气泡合并

液体脉冲激光烧蚀（LAL）是一种合成成分可控、高纯度纳米颗粒的方法。然而，目前的研究主要检查孤立的空化气泡，忽略了现实世界中大量气泡同时相互作用的鲎溶液场景。本研究通过研究液体中短程微米空间控制双脉冲激光烧蚀对纳米颗粒尺寸分布的影响来解决这一差距。以金和YAG为模型材料，引入无量纲参数H * 来量化双气泡空间分离与其最大高度之间的比率。该参数与空化气泡合并时间、气泡体积变化率以及随后的纳米颗粒尺寸增加相关。阴影图为气泡接触和融合动力学提供了宝贵的见解，展示了薄水膜的相分离以及随后合并成单个气泡的情况。值得注意的是，在H * = 0.25时，Au 和 YAG 的纳米颗粒尺寸均增加了一倍。研究表明，纳米颗粒尺寸趋势与空化气泡体积速率变化之间存在密切关联，特别是在H * = 0.25 时。了解 LAL 过程中相邻气泡的动态强调了双束 LAL 中横向脉冲距离的相关性，以距离相关的方式影响颗粒尺寸分布。