飞秒激光照射金纳米颗粒的分子动力学模拟

在分子动力学的基础上引入了双温度模型,对飞秒激光照射金纳米颗粒的相变传热过程进行了模拟研究。利用序参数法对传热过程中颗粒内部固液相变的发生进行了判别,并获取了纳米颗粒受飞秒激光照射的熔化特性,在此基础上研究了不同大小的激光能量对熔化过程的影响。结果表明,在飞秒激光照射金纳米颗粒的过程中,当颗粒内部相变发生时,金原子的空间分布由面心立方规则排列逐渐变为不规则无序的松散排列,纳米颗粒内部所有区域都发生了熔化现象,不存在一个明显的固液模拟界面。随着激光的不断照射,熔化比例逐渐增加。

Molecular Dynamics Simulation of the Femtosecond Laser Melting of Au Nanoparticles

An Au nanoparticle irradiated by a femtosecond laser pulse was simulated with a modified molecular dynamics model. The local order parameter method was used to distinguish solid and liquid phase atoms and the melting characteristics of particles were obtained. The influence of different intensities of laser energy on the melting process was also explored. The results show that the spatial distribution of the gold atoms is transfered from the face centered cubic (FCC) to the loose arrangement of irregular disorder when the phase change occurs. It can be found that the melting process is a full scale melting, there is not an apparent interface between solid and liquid. And the proportion of melting increases gradually with the continuous laser irradiating.