Numerous valuable studies on electron dynamics have focussed on the extraordinary properties of molybdenum disulfide (MoS2); however, most of them were confined to the level below the damage threshold. Here the electron dynamics of MoS2 under intense ultrafast laser irradiation was investigated by experiments and simulations. Two kinds of ablation mechanisms were revealed, which led to two distinct types of electron dynamics and final ablation morphology. At a higher fluence, the emergence of superheated liquid induced a dramatic change in the transient reflectivity and micro-honeycomb structures. At a lower fluence, the material was just removed by sublimation, and the ablation structure was relatively flat. X-ray photoelectron spectroscopic (XPS) measurements demonstrated that thermal decomposition only occurred at the higher fluence. Furthermore, a theoretical model was developed to deeply reveal the ultrafast dynamics of MoS2 ablation. The simulation results were in good agreement with the temporal and spatial reflectivity distribution obtained from the experiment. The electron and lattice temperature evolution was also obtained to prove the ablation mechanism. Our results revealed ultrafast dynamics of MoS2 above the damage threshold and are helpful for understanding the interaction mechanism between MoS2 and intense ultrafast lasers, as well as for MoS2 processing applications.

中文翻译：

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飞秒激光辐照下二硫化钼的超快光学响应和烧蚀机理。

关于电子动力学的许多有价值的研究都集中在二硫化钼（MoS2）的非凡性能上。但是，大多数都被限制在损害阈值以下。在这里，通过实验和模拟研究了强超快激光辐照下MoS2的电子动力学。揭示了两种烧蚀机理，其导致两种不同类型的电子动力学和最终烧蚀形态。在较高的通量下，过热液体的出现引起瞬态反射率和微蜂窝结构的急剧变化。在较低的注量下，仅通过升华去除材料，并且消融结构相对平坦。X射线光电子能谱（XPS）测量表明，热分解仅在较高的通量下发生。此外，建立了理论模型以深刻揭示MoS2消融的超快动力学。仿真结果与实验得到的时空反射率分布吻合良好。还获得了电子和晶格温度的演化，以证明烧蚀机理。我们的研究结果表明，MoS2的超快动力学超过了损伤阈值，有助于理解MoS2和强超快激光之间的相互作用机理，以及对MoS2加工应用的帮助。还获得了电子和晶格温度的演化，以证明烧蚀机理。我们的研究结果表明，MoS2的超快动力学超过了损伤阈值，有助于理解MoS2和强超快激光之间的相互作用机理，以及对MoS2加工应用的帮助。还获得了电子和晶格温度的演化，以证明烧蚀机理。我们的研究结果表明，MoS2的超快动力学超过了损伤阈值，有助于理解MoS2和强超快激光之间的相互作用机理，以及对MoS2加工应用的帮助。