Femtosecond laser induced desorption of H2, D2, and HD from Ru(0001): Dynamical promotion and suppression studied with ab initio molecular dynamics with electronic friction
Femtosecond laser induced desorption of H2, D2, and HD from Ru(0001): Dynamical promotion and suppression studied with ab initio molecular dynamics with electronic friction
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DOI：
10.1103/physrevb.95.125439
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发表时间：
2017-03-29
影响因子：
3.7
通讯作者：
Saalfrank, P.
中科院分区：
文献类型：
--
作者：
Juaristi, J. I.;Alducin, M.;Saalfrank, P.
我们进行从头算分子动力学模拟来研究飞秒激光诱导H-2、D-2和HD从H: d饱和Ru（0001）表面的解吸。为此，我们扩展了带电子摩擦的从头算分子动力学（AIMDEF）方案，以包括随时间变化的电子温度函数的随机力。后者根据双温度模型表征了超短激光脉冲的作用。这使我们能够进行多维的，热电子驱动的反应动力学，并研究脱附产率对表面上相对H: D同位素浓度的依赖。我们的AIMDEF模拟表明，解吸过程发生在加热的吸附体系中，这明显影响了解吸动力学。较轻（较重）同位素的浓度越大，吸附质系统的升温越明显（越不明显）。因此，我们得出结论，表面上H的存在有利于分子的解吸，而D的存在阻碍了分子的解吸，这与先前的实验观察一致，其中表面反应的“动态促进”现象已经被假设。
We perform ab initio molecular dynamics simulations to study the femtosecond laser induced desorption of H-2, D-2, and HD from a H: D-saturated Ru(0001) surface. To this aim we have extended the ab initio molecular dynamics with electronic friction (AIMDEF) scheme to include a random force that is a function of a timedependent electronic temperature. The latter characterizes the action of the ultrashort laser pulse according to a two temperature model. This allows us to perform multidimensional, hot-electron driven reaction dynamics and investigate the dependence of the desorption yields on the relative H: D isotope concentration on the surface. Our AIMDEF simulations show that the desorption process takes place in the presence of a heated adsorbate system that clearly influences the desorption dynamics. The heating of the adsorbate system is more (less) pronounced the larger is the concentration of the lighter (heavier) isotope. As a result, we conclude that the presence of H on the surface favors the desorption of molecules, whereas the presence of D hampers it, in agreement with previous experimental observations in which the phenomenon of "dynamical promotion" of a surface reaction had been postulated.