It is necessary to understand the light-matter interaction for application of femtosecond laser micro/nanoprocessing. In this work, the authors investigated the melting and disintegration behavior of a Cu film irradiated by a femtosecond laser with different pulse durations in the range of 35–500 fs by using a combined two temperature model (TTM) and molecular dynamics (MD) method. On the basis of TTM-MD, the temperature and stress evolution of the Cu film were analyzed. The result indicated that the Cu film disintegrates when the pulse duration is shorter than 100 fs but melts at a pulse duration of 200 fs. The photomechanical and thermomechanical evolutions induced by the femtosecond laser were also analyzed. The stress wave and increasing temperature were the main reasons for film disintegration and vibration. The snapshots of the Cu film indicate the melting and disintegration processes on an atomic scale. It shows that the melting occurs homogeneously, whereas the disintegration occurs at the center of the film. These results are helpful to understand the mechanism of femtosecond laser materials ablation.

中文翻译：

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不同脉宽飞秒激光辐照铜膜的原子模拟

了解飞秒激光微/纳米加工应用的光-物质相互作用是必要的。在这项工作中，作者使用组合的两种温度模型 (TTM) 和分子动力学 (MD) 方法研究了在 35-500 fs 范围内不同脉冲持续时间的飞秒激光照射下的 Cu 膜的熔化和崩解行为. 在TTM-MD的基础上，分析了Cu膜的温度和应力演化。结果表明，当脉冲持续时间短于 100 fs 时，Cu 膜解体，而在 200 fs 的脉冲持续时间下熔化。还分析了由飞秒激光引起的光机械和热机械演变。应力波和温度升高是薄膜崩解和振动的主要原因。Cu 薄膜的快照显示了原子尺度上的熔化和分解过程。它表明熔化均匀发生，而崩解发生在薄膜的中心。这些结果有助于理解飞秒激光材料烧蚀的机理。