Kang Peiyuan, Wang Yang, Wilson Blake A, Liu Yaning, Dawkrajai Napat, Randrianalisoa Jaona, Qin Zhenpeng
Department of Mechanical Engineering, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States.
Institut de Thermique, Mécanique, Matériaux (ITheMM EA 7548), University of Reims Champagne-Ardenne, Reims, Cedex 2 51687, France.
J Phys Chem C Nanomater Interfaces. 2021 Dec 9;125(48):26718-26730. doi: 10.1021/acs.jpcc.1c06684. Epub 2021 Nov 24.
Understanding the laser-nanomaterials interaction including nanomaterial fragmentation has important implications in nanoparticle manufacturing, energy, and biomedical sciences. So far, three mechanisms of laser-induced fragmentation have been recognized including non-thermal processes and thermomechanical force under femtosecond pulses, and the phase transitions under nanosecond pulses. Here we show that single picosecond (ps) laser pulse stimulation leads to anomalous fragmentation of gold nanoparticles that deviates from these three mechanisms. The ps laser fragmentation was weakly dependent on particle size, and it resulted in a bimodal size distribution. Importantly, ps laser stimulation fragmented particles below the whole particle melting point and below the threshold for non-thermal mechanism. We propose a framework based on near-field enhancement and nanoparticle surface melting to account for the ps laser-induced fragmentation observed here. This study reveals a new form of surface ablation that occurs under picosecond laser stimulation at low fluence.
了解激光与纳米材料的相互作用，包括纳米材料的破碎，在纳米颗粒制造、能源和生物医学科学领域具有重要意义。到目前为止，已确认了三种激光诱导破碎机制，包括飞秒脉冲下的非热过程和热机械力，以及纳秒脉冲下的相变。在此我们表明，单个皮秒（ps）激光脉冲刺激会导致金纳米颗粒出现异常破碎，这与上述三种机制不同。皮秒激光破碎对颗粒尺寸的依赖性较弱，并且会导致双峰尺寸分布。重要的是，皮秒激光刺激在整个颗粒熔点以下且低于非热机制阈值的情况下使颗粒破碎。我们提出了一个基于近场增强和纳米颗粒表面熔化的框架，以解释此处观察到的皮秒激光诱导破碎现象。这项研究揭示了一种在低能量密度皮秒激光刺激下发生的新型表面烧蚀形式。
