Desorption kinetics from a surface derived from direct imaging of the adsorbate layer.
Desorption kinetics from a surface derived from direct imaging of the adsorbate layer.
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来自吸附层直接成像的表面解吸动力学。
DOI：
10.1038/ncomms4853
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发表时间：
2014
影响因子：
16.6
通讯作者：
Günther S
中科院分区：
文献类型：
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作者：
Günther S
激光烧蚀已广泛用于各种应用。由于烧蚀机制很大程度上取决于光激发水平，因此所谓的冷材料加工依赖于高峰值功率激光能量密度的使用，其中非热过程占主导地位；在大多数固体中，通常达到~1 J cm−2 等离子体形成的通用阈值。在这里，我们展示了单次时间分辨飞秒电子衍射、飞秒光学反射率和离子检测实验，以研究结晶氯化钠、碘化铯和碘化钾中飞秒 400 nm 激光激发后的烧蚀过程的演变。这类材料中的现象发生在远低于等离子体形成阈值，甚至低于熔点的情况下。结果揭示了快速的电子和局部结构变化，导致颗粒喷射和微米深弹坑的形成，反映了强排斥力的本质。
Laser ablation has been widely used for a variety of applications. Since the mechanisms for ablation are strongly dependent on the photoexcitation level, so called cold material processing has relied on the use of high-peak-power laser fluences for which nonthermal processes become dominant; often reaching the universal threshold for plasma formation of ~1 J cm−2in most solids. Here we show single-shot time-resolved femtosecond electron diffraction, femtosecond optical reflectivity and ion detection experiments to study the evolution of the ablation process that follows femtosecond 400 nm laser excitation in crystalline sodium chloride, caesium iodide and potassium iodide. The phenomenon in this class of materials occurs well below the threshold for plasma formation and even below the melting point. The results reveal fast electronic and localized structural changes that lead to the ejection of particulates and the formation of micron-deep craters, reflecting the very nature of the strong repulsive forces at play.