Kalus Mark-Robert, Barcikowski Stephan, Gökce Bilal
Technical Chemistry I, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141, Essen, Germany.
Materials Science and Additive Manufacturing, School of Mechanical Engineering and Safety Engineering, University of Wuppertal, 42119, Wuppertal, Germany.
Chemistry. 2021 Apr 1;27(19):5978-5991. doi: 10.1002/chem.202005087. Epub 2021 Mar 4.
Understanding the key steps that drive the laser-based synthesis of colloids is a prerequisite for learning how to optimize the ablation process in terms of nanoparticle output and functional design of the nanomaterials. Even though many studies focus on cavitation bubble formation using single-pulse ablation conditions, the ablation efficiency and nanoparticle properties are typically investigated under prolonged ablation conditions with repetition rate lasers. Linking single-pulse and multiple-pulse ablation is difficult due to limitations induced by gas formation cross-effects, which occur on longer timescales and depend on the target materials' oxidation-sensitivity. Therefore, this study investigates the ablation and cavitation bubble dynamics under nanosecond, single laser pulse conditions for six different bulk materials (Au, Ag, Cu, Fe, Ti, and Al). Also, the effective threshold fluences, ablation volumes, and penetration depths are quantified for these materials. The thermal and chemical properties of the corresponding bulk materials not only favor the formation of larger spot sizes but also lead to the highest molar ablation efficiencies for low melting materials such as aluminum. Furthermore, the concept of the cavitation bubble growth linked with the oxidation sensitivity of the ablated material is discussed. With this, evidence is provided that intensive chemical reactions occurring during the very early timescale of ablation are significantly enhanced by the bubble collapse.
了解驱动基于激光的胶体合成的关键步骤,是学习如何在纳米颗粒产量和纳米材料功能设计方面优化烧蚀过程的先决条件。尽管许多研究聚焦于单脉冲烧蚀条件下的空化气泡形成,但烧蚀效率和纳米颗粒特性通常是在重复频率激光的长时间烧蚀条件下进行研究的。由于气体形成交叉效应所导致的限制,将单脉冲和多脉冲烧蚀联系起来很困难,这种交叉效应发生在更长的时间尺度上,并且取决于靶材的氧化敏感性。因此,本研究调查了六种不同块状材料(金、银、铜、铁、钛和铝)在纳秒单激光脉冲条件下的烧蚀和空化气泡动力学。此外,还对这些材料的有效阈值能量密度、烧蚀体积和穿透深度进行了量化。相应块状材料的热学和化学性质不仅有利于形成更大的光斑尺寸,而且对于低熔点材料(如铝)还能带来最高的摩尔烧蚀效率。此外,还讨论了与被烧蚀材料的氧化敏感性相关的空化气泡生长概念。由此提供的证据表明,烧蚀最早期阶段发生的剧烈化学反应会因气泡坍塌而显著增强。