Gou F, Gleeson M A, Kleyn A W
Gorlaeus Laboratories, Leiden Institute of Chemistry, 2300 RA Leiden, The Netherlands.
Phys Chem Chem Phys. 2006 Dec 21;8(47):5522-34. doi: 10.1039/b611739b. Epub 2006 Oct 25.
We have simulated CF scattering from Si(100) using the molecular dynamics method. Translational energy loss spectra are presented. The shape of the energy loss distribution as a result of internal energy release is analyzed. At the classical turning point, the internal energy of the molecule is mainly in the form of rotational energy. The strong rotational excitation results in additional molecule-surfaces interactions during the latter half of the collision. These additional collisions permit some molecules that initially gain internal energy exceeding the bond strength to ultimately survive the collision process via rotational de-excitation. The rotational motion exhibited by surviving molecules is determined by the combination of the molecular axis orientation and the local surface structure during the collision process. The rotation planes of the surviving molecules are preferentially aligned with the surface normal (cartwheel-like and propeller-like motions). In this study, propeller-like motion of the surviving molecules is predicted. The majority of surviving molecules exhibit a cartwheel-like motion. However, molecules that gain a propeller-like rotation exhibit a much better alignment of their planes-of-rotation compared with molecules exhibiting cartwheel-like motion.
我们使用分子动力学方法模拟了CF从Si(100)的散射。给出了平动能损失谱。分析了由于内能释放导致的能量损失分布的形状。在经典转折点，分子的内能主要以转动能的形式存在。强烈的转动激发导致在碰撞的后半段分子与表面之间产生额外的相互作用。这些额外的碰撞使得一些最初获得超过键强的内能的分子最终通过转动去激发在碰撞过程中存活下来。存活分子所表现出的转动运动由碰撞过程中分子轴取向和局部表面结构的组合决定。存活分子的转动平面优先与表面法线对齐（类似车轮和螺旋桨的运动）。在本研究中，预测了存活分子的螺旋桨状运动。大多数存活分子表现出类似车轮的运动。然而，与表现出类似车轮运动的分子相比，获得螺旋桨状转动的分子其转动平面的排列要好得多。
