Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion
Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion
复制标题
Ru(0001) 上 CO 的飞秒激光诱导动力学：包括表面运动在内的热电子摩擦模型的深刻见解
DOI：
10.1103/physrevb.94.165447
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发表时间：
2016
影响因子：
3.7
通讯作者：
J.I. Juaristi
中科院分区：
文献类型：
--
作者：
R. Scholz;G. Floß;P. Saalfrank;G. Füchsel;I. Loncaric;J.I. Juaristi
考虑到所有六个分子自由度的Langevin模型应用于飞秒激光诱导的热电子驱动的Ru（0001）（）：CO的动力学。在我们的分子动力学与电子摩擦方法中，采用了最近发展的基于梯度修正的密度泛函理论的势能面占货车德瓦尔斯相互作用。电子摩擦，由于耦合的分子自由度的电子-空穴对在金属中包括通过局部密度摩擦近似，和表面声子的广义朗之万振子模型。超短激光脉冲的作用是通过基质介导的热电子机制，通过随时间变化的电子温度（来自双温度模型）进入，引起作用在分子上的随机力。该模型适用于激光诱导的横向扩散的CO表面上，“热吸附”的形成，和激光诱导脱附。与纯热过程相比，扩散和解吸的反应概率都大大提高。反应产率取决于所施加的激光能量密度的特征（非线性）的方式，以及各种反应通道的分支比。计算的两个脉冲的相关性痕迹解吸和其他指标表明，除了电子空穴对，声子在这个系统中的激光诱导动力学发挥不可忽视的作用，作用在一个令人惊讶的短时间尺度。我们的模拟预先计算的潜力，允许良好的统计和治疗的长时间动态（300 ps），深入了解这个系统，迄今尚未达到。我们发现，一般与实验数据的良好协议，并作出预测。最近提出的激光诱导人口的物理吸附的前体状态不能观察到目前的低覆盖率模型。
A Langevin model accounting for all six molecular degrees of freedom is applied to femtosecond-laser induced, hot-electron driven dynamics of Ru(0001)():CO. In our molecular dynamics with electronic friction approach, a recently developed potential energy surface based on gradient-corrected density functional theory accounting for van der Waals interactions is adopted. Electronic friction due to the coupling of molecular degrees of freedom to electron-hole pairs in the metal are included via a local density friction approximation, and surface phonons by a generalized Langevin oscillator model. The action of ultrashort laser pulses enters through a substrate-mediated, hot-electron mechanism via a time-dependent electronic temperature (derived from a two-temperature model), causing random forces acting on the molecule. The model is applied to laser induced lateral diffusion of CO on the surface, “hot adsorbate” formation, and laser induced desorption. Reaction probabilities are strongly enhanced compared to purely thermal processes, both for diffusion and desorption. Reaction yields depend in a characteristic (nonlinear) fashion on the applied laser fluence, as well as branching ratios for various reaction channels. Computed two-pulse correlation traces for desorption and other indicators suggest that aside from electron-hole pairs, phonons play a non-negligible role for laser induced dynamics in this system, acting on a surprisingly short time scale. Our simulations on precomputed potentials allow for good statistics and the treatment of long-time dynamics (300 ps), giving insight into this system which hitherto has not been reached. We find generally good agreement with experimental data where available and make predictions in addition. A recently proposed laser induced population of physisorbed precursor states could not be observed with the present low-coverage model.