Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm, Germany.
Phys Chem Chem Phys. 2011 May 21;13(19):8659-70. doi: 10.1039/c0cp02086a. Epub 2011 Mar 2.
An electronic friction approach based on Langevin dynamics is used to describe the multidimensional (six-dimensional) dynamics of femtosecond laser induced desorption of H(2) and D(2) from a H(D)-covered Ru(0001) surface. The paper extends previous reduced-dimensional models, using a similar approach. In the present treatment forces and frictional coefficients are calculated from periodic density functional theory (DFT) and essentially parameter-free, while the action of femtosecond laser pulses on the metal surface is treated by using the two-temperature model. Our calculations shed light on the performance and validity of various adiabatic, non-adiabatic, and Arrhenius/Kramers type kinetic models to describe hot-electron mediated photoreactions at metal surfaces. The multidimensional frictional dynamics are able to reproduce and explain known experimental facts, such as strong isotope effects, scaling of properties with laser fluence, and non-equipartitioning of vibrational, rotational, and translational energies of desorbing species. Further, detailed predictions regarding translations are made, and the question for the controllability of photoreactions at surfaces with the help of vibrational preexcitation is addressed.
基于朗之万动力学的电子摩擦方法被用于描述飞秒激光诱导 H(D)-覆盖的 Ru(0001)表面上 H(D)分子离解的多维（六维）动力学。该论文扩展了之前的降维模型，使用了类似的方法。在目前的处理中，力和摩擦系数是根据周期性密度泛函理论（DFT）计算的，基本上是无参数的，而飞秒激光脉冲对金属表面的作用则通过使用双温模型来处理。我们的计算揭示了各种绝热、非绝热和 Arrhenius/Kramers 类型的动力学模型在描述金属表面热电子介导的光反应时的性能和有效性。多维摩擦动力学能够再现和解释已知的实验事实，例如强同位素效应、激光强度依赖性、离解物种的振动、转动和平动能量的非等配分。此外，还对平移进行了详细的预测，并讨论了通过振动预激发控制表面光反应的可能性。
