乙炔在Ge(001)表面吸附的反应路径(英文)

Reaction Pathways of Acetylene Adsorption on the Ge(001)Surface

采用第一性原理方法研究了乙炔分子在Ge(001)表面的吸附反应.通过系统考察0.5和1.0ML覆盖度时形成di-σ和end-bridge构型的反应路径,研究在表面形成di-σ和paired-end-bridge构型的反应几率.除了表面反应以外,本文还涉及了亚表层Ge原子参与的吸附反应,乙炔在亚表层原子上吸附形成的亚稳态结构sub-di-σ,是形成end-bridge结构的第二条途径,此反应机理对于表面吸附结构的形成起重要的作用.与乙炔分子不同的是,表面以下原子参与时乙烯分子的吸附反应为吸热反应.综合热力学和动力学的分析表明,paired-end-bridge构型是乙炔分子吸附的主要构型,此结论解释了乙炔分子在Ge(001)表面吸附构型的实验结果.对于乙烯和乙炔两分子在Ge(001)表面吸附的分析比较揭示了导致两者之间差异的原因.

The adsorption reaction of acetylene on the Ge（001）surface is investigated by first-principles calculations.In order to understand the relative populations of the di-σand paired-end-bridge structures,we calculated the adsorption reaction paths leading to their formation at 0.5 and 1.0 ML coverage.More importantly,we studied the adsorption channel involving sublayer Ge atoms by forming a metastable sub-di-σstructure.This sub-di-σstructure represents second reaction pathway that results in the end-bridge structure,which plays an important role in the formation of the adsorption configurations.In contrast to C 2 H 2,the adsorption of C 2 H 4 on the Ge（001）surface involving subsurface Ge atoms,is endothermic.Our calculations show from both kinetic and thermodynamic standpoints that the paired-end-bridge structure is the primary adsorption configuration that explains the experimental observations.Our work also helps to understand the fundamental differences between the adsorption of C 2 H 2 and C 2 H 4 on the Ge（001）surface.