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首页> 外文会议>High-Power Laser Ablation VI pt.1 >Thermal excitation of d band electrons in Au: implications for laser-induced phase transformations
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Thermal excitation of d band electrons in Au: implications for laser-induced phase transformations

机译：Au中d带电子的热激发：对激光诱导的相变的影响

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摘要

The temperature dependences of the electron heat capacity and the electron-phonon coupling factor are investigated for Au based on the electron density of states obtained from ab initio electronic structure calculations. Thermal excitation of d band electrons leads to a significant (up to an order of magnitude) increase in the electron-phonon coupling factor and makes a considerable contribution to the electron heat capacity in the range of electron temperatures typically realized in femtosecond laser material processing applications. Simulations performed with a combined atomistic-continuum method demonstrate that the increase in the strength of the electron-phonon coupling at high electron temperatures leads to a faster lattice heating, generation of stronger thermoelastic stresses, and a significant decrease in the time of the onset of the melting process. The timescale of the melting process predicted in the simulation accounting for the thermal excitation of d band electrons is in excellent agreement with the results of recent time-resolved electron diffraction experiments. A simulation performed with commonly used approximations of a constant electron-phonon coupling factor and a linear temperature dependence of the electron heat capacity, on the other hand, significantly overpredicts the time of the beginning of the melting process, supporting the importance of the electron density of states effects and thermal excitation of lower band electrons for realistic modeling of femtosecond pulse laser processing.
机译：基于从头算电子结构计算获得的态的电子密度，研究了Au的电子热容量和电子-声子耦合因子的温度依赖性。 d波段电子的热激发导致电子-声子耦合因子的显着（高达一个数量级）增加，并且在飞秒激光材料加工应用中通常实现的电子温度范围内，对电子热容量做出了相当大的贡献。用组合原子-连续谱方法进行的仿真表明，在高电子温度下，电子-声子耦合强度的增加导致晶格加热更快，产生更强的热弹性应力，并且显着减少了电子的发生时间。融化的过程。在模拟中预测的熔解过程的时间尺度，考虑了d带电子的热激发，与最近的时间分辨电子衍射实验的结果非常吻合。另一方面，使用恒定的电子-声子耦合因子和电子热容量的线性温度依赖性的常用近似值进行的模拟大大地预测了熔化过程的开始时间，从而支持了电子密度的重要性飞秒脉冲激光加工的逼真建模的低能带电子的状态效应和热激发分析

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