Numerical Simulation of Ejected Molten Metal Nanoparticles Liquified by Laser Irradiation: Interplay of Geometry and Dewetting
Numerical Simulation of Ejected Molten Metal Nanoparticles Liquified by Laser Irradiation: Interplay of Geometry and Dewetting
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DOI：
10.1103/physrevlett.111.034501
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发表时间：
2013-07-16
影响因子：
8.6
通讯作者：
Kondic, L.
中科院分区：
文献类型：
--
作者：
Afkhami, S.;Kondic, L.
金属纳米粒子被快速激光照射液化后，会经历快速的形状变化，试图将其表面能量降至最低。当导致去湿的机制足够强时，产生的纳米液滴可以从衬底中喷射出来，就像涉及金纳米粒子的实验一样[Habenicht等人，科学309,2043(2005)]。我们使用直接连续水平的方法来精确地模拟液体纳米液滴的形成和随后从衬底上喷射的过程。我们的计算显示了惯性效应的重要作用以及初始几何形状和润湿性质的精细相互作用：例如，我们可以通过规定适当的初始形状和/或润湿性质来控制喷射的方向。通过考虑一个基于能量平衡的简单有效的模型，可以得出关于射出本身的基本见解。我们通过直接与上面指定的实验进行比较来验证我们的计算，这些实验涉及以数百纳米测量的长度尺度，以及以数十个原子直径测量的更短尺度的分子动力学模拟，正如M.Fuentes-Cabrera等人所做的那样。[物理。修订本E 83,041603(2011年)]。这种定量的一致性，除了说明如何控制粒子抛射外，还表明了基于连续介质的模拟在定量描述纳米尺度上的动力学方面的有效性，即使在这里所考虑的复杂环境中也是如此。
Metallic nanoparticles, liquified by fast laser irradiation, go through a rapid change of shape attempting to minimize their surface energy. The resulting nanodrops may be ejected from the substrate when the mechanisms leading to dewetting are sufficiently strong, as in the experiments involving gold nanoparticles [Habenicht et al., Science 309, 2043 (2005)]. We use a direct continuum-level approach to accurately model the process of liquid nanodrop formation and the subsequent ejection from the substrate. Our computations show a significant role of inertial effects and an elaborate interplay of initial geometry and wetting properties: e.g., we can control the direction of ejection by prescribing appropriate initial shape and/or wetting properties. The basic insight regarding ejection itself can be reached by considering a simple effective model based on an energy balance. We validate our computations by comparing directly with the experiments specified above involving the length scales measured in hundreds of nanometers and with molecular dynamics simulations on much shorter scales measured in tens of atomic diameters, as by M. Fuentes-Cabrera et al. [Phys. Rev. E 83, 041603 (2011)]. The quantitative agreement, in addition to illustrating how to control particle ejection, shows utility of continuum-based simulation in describing dynamics on nanoscale quantitatively, even in a complex setting as considered here.