One-step laser-assisted fabrication of elongated Au nanoparticles (NPs) and their subsequent fragmentation and agglomeration are experimentally studied. The generation of elongated Au NPs is carried out via laser ablation of a solid Au target in water using an ytterbium-doped fiber laser source with pulse duration of 200 ns and pulse energy of 1 mJ. Extinction spectrum of the resulting particles exhibits an increase in the absorption in visible red and near IR spectral regions. This change in absorption is accounted for by the longitudinal plasmon resonance of the electrons in elongated Au NPs and is corroborated by the TEM images. The effect of additional laser exposure on the elongated Au NPs produced using this method is studied, as well. Laser pulse energies and exposure times are varied. Possible processes of laser-assisted formation of elongated Au NPs in aqueous solutions of calcium chloride and magnesium sulfate and their following interaction with pulsed laser radiation are discussed.

中文翻译：

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激光辅助在二价离子水溶液中生成细长的金纳米粒子

实验研究了一步激光辅助制造细长 Au 纳米粒子 (NPs) 及其随后的碎裂和团聚。使用脉冲持续时间为 200 ns 和脉冲能量为 1 mJ 的掺镱光纤激光源，通过在水中对固体 Au 目标进行激光烧蚀来生成细长的 Au NP。所得颗粒的消光光谱在可见红光和近红外光谱区的吸收增加。这种吸收变化是由细长的 Au NP 中电子的纵向等离子体共振引起的，并由 TEM 图像证实。还研究了额外的激光曝光对使用这种方法生产的细长 Au NP 的影响。激光脉冲能量和曝光时间是变化的。