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首页> 外文期刊>Physical review >Expansion-limited aggregation of nanoclusters in a single-pulse laser-produced plume
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Expansion-limited aggregation of nanoclusters in a single-pulse laser-produced plume

机译：纳米团簇在单脉冲激光产生羽流中的扩展受限聚集

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摘要

Formation of carbon nanoclusters in a single-laser-pulse created ablation plume was studied both in vacuum and in a noble gas environment at various pressures. The developed theory provides cluster radius dependence on combination of laser parameters, properties of ablated material, and type and pressure of an ambient gas in agreement with experiments. The experiments were performed on carbon nanoclusters formed by laser ablation of graphite targets with 12 picosecond 532 nm laser pulses at MHz-range repetition rate in a broad range of ambient He, Ar, Kr, and Xe gas pressures from 2 × 10~(-2) to 1500 Torr. The experimental results confirmed our theoretical prediction that the average size of the nanoparticles depends weakly on the type of the ambient gas used, and is determined exclusively by the single laser pulse parameters even at the repetition rate as high as 28 MHz with the time gap 36 ns between the pulses. The most important finding relates to the fact that in vacuum the cluster size is mainly determined by hydrodynamic expansion of the plume while in the ambient gas it is controlled by atomic diffusion in the gas. We demonstrate that the ultrashort pulses can be used for production of clusters with the size less than the critical value, which separates the particles with properties drastically different from those of a material in a bulk. The presented results of experiments on formation of carbon nanoclusters are in close agreement with the theoretical scaling. The developed theory is applicable for cluster formation from any monatomic material, such as silicon for example.
机译：在真空和稀有气体环境中，在各种压力下，研究了单激光脉冲产生的烧蚀羽流中碳纳米团簇的形成。发达的理论提供了与实验参数相一致的，取决于激光参数，烧蚀材料的性质以及环境气体的类型和压力的组合的团簇半径。实验是在12×皮秒532 nm激光脉冲以兆赫范围重复率在2×10〜（- 2）至1500托。实验结果证实了我们的理论预测，即纳米颗粒的平均尺寸几乎不依赖于所用环境气体的类型，并且即使在重复频率高达28 MHz且间隔为36的情况下，也仅由单个激光脉冲参数确定脉冲之间的ns。最重要的发现与以下事实有关：在真空中，团簇的大小主要取决于羽流的流体动力膨胀，而在环境气体中，其大小由气体中的原子扩散控制。我们证明，超短脉冲可用于生产尺寸小于临界值的团簇，从而将颗粒的性质与散装材料的性质截然不同。所提出的碳纳米团簇形成实验结果与理论尺度吻合。发达的理论适用于由任何单原子材料（例如硅）形成团簇。

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  • 来源
    《Physical review》 |2009年第18期|184113.1-184113.12|共12页
  • 作者

    E. G. Gamaly; N. R. Madsen; D. Golberg; A. V. Rode;

  • 作者单位

    Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia;

    Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia Australian Patent Office, Woden, Australian Capital Territory 2606, Australia;

    World Premier International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan;

    Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia;

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  • 正文语种 eng
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  • 关键词

    nanoscale materials and structures: fabrication and characterization; nanocrystals and nanoparticles; laser ablation;

    机译：纳米级材料和结构：制造和表征;纳米晶体和纳米颗粒;激光烧蚀;

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