The mechanism of the shape elongation of metal nanoparticles (NPs) in silica, which is induced under swift heavy ion irradiation, is discussed with comparing the two candidates: (i) the synergy between the ion hammering and the transient melting of NPs by the inelastic thermal spike and (ii) the thermal pressure and flow model. We show that three experimental results are inconsistent with (i). The latter is supported by two-temperature molecular dynamics simulations, which simulate not only the atomic motions but also the local electron temperatures. A remarkable correlation was observed between the temporal evolution of the silica density around the ion trajectory and that of the aspect ratio of the NP later than ~ 1 ps after the ion impact, while no correlation was observed earlier than ~ 1 ps, even under the assumption of the instantaneous energy deposition.

通过比较两个候选物，讨论了在快速重离子辐照下诱导的二氧化硅中金属纳米颗粒（NPs）形状伸长的机理：（i）离子锤击与非弹性瞬态熔化之间的协同作用热峰值和（ii）热压力和流量模型。我们显示三个实验结果与（i）不符。后者由两个温度的分子动力学模拟支持，该模拟不仅模拟原子运动，而且模拟局部电子温度。观察到离子轨迹周围的二氧化硅密度的时间演变与离子撞击后晚于约1 ps的NP的纵横比之间存在显着相关性，而早于〜1 ps则没有相关性，