Experimental and Theoretical Investigation of Periodic Nanostructuring of Au with Ultrashort UV Laser Pulses near the Damage Threshold
Experimental and Theoretical Investigation of Periodic Nanostructuring of Au with Ultrashort UV Laser Pulses near the Damage Threshold
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DOI：
10.1103/physrevapplied.4.064006
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发表时间：
2015-12-18
影响因子：
4.6
通讯作者：
Simon, P.
中科院分区：
文献类型：
--
作者：
Ivanov, D. S.;Lipp, V. P.;Simon, P.
超短激光脉冲对固体表面结构的重构涉及多个快速、非平衡和相互关联的过程，而固体处于瞬态。因此，对实验数据的分析不能解决纳米结构的所有机制。在本文中，我们直接比较了单脉冲激光诱导表面纳米修饰的模拟结果和实验结果。实验结果采用掩模投影装置，激光波长为248 nm，脉冲长度为1.6 ps。该短波长的双光束干涉可以在周期为500 nm的正弦形状的金表面上产生直径为40 μ m的大面积强光栅。利用扫描电子显微镜（SEM）和透射电子显微镜（TEM）分别在表面和截面上分析了形成的结构。然后，利用能够捕捉纳米结构过程基本机制的混合原子-连续介质模型来模拟激光脉冲与厚金靶的相互作用。建模结果和实验数据之间的良好一致性证明了所提出的方法是一个强大的工具，揭示了金表面纳米结构过程背后的物理原理，并提供了对金属结构过程动力学的微观洞察。因此，所提出的模型是在原子尺度上预测材料对超短激光脉冲响应的计算工具的重要一步。这种对过程动力学的详细理解将为纳米尺度和微尺度上功能化表面的预先设计拓扑铺平道路。
The mechanism of surface restructuring by ultrashort laser pulses involves a number of fast, nonequilibrium, and interrelated processes while the solid is in a transient state. As a result, the analysis of the experimental data cannot address all of the mechanisms of nanostructuring. In this paper, we present a direct comparison of a simulation and the experimental results of surface nanomodifications induced by a single laser pulse. The experimental results are obtained by using a mask-projection setup with a laser wavelength of 248 nm and a pulse length of 1.6 ps. Two-beam interference of this short wavelength allows for producing a large-area intensity grating of 40 mu m in diameter on a gold surface with a sinusoidal shape and a period of 500 nm. The formed structures are analyzed at the surface and in a cross section by a scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. Then a hybrid atomistic-continuum model capable of capturing the essential mechanisms responsible for the nanostructuring process is used to model the interaction of the laser pulse with a thick gold target. The good agreement between the modeling results and the experimental data justifies the proposed approach as a powerful tool revealing the physics behind the nanostructuring process at a gold surface and providing a microscopic insight into the dynamics of the structuring processes of metals in general. The presented model, therefore, is an important step towards a computational tool for predicting a materials response to an ultrashort laser pulse on the atomic scale. This detailed understanding of the dynamics of the process will pave the way towards predesigned topologies for functionalized surfaces on nanoscales and microscales.