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Stereodynamics of Chemical Reactions on Solid Surfaces Induced by Molecules and Radicals

分子和自由基诱导的固体表面化学反应的立体动力学

基本信息

批准号：
17550011
负责人：
OKADA Michio
金额：
$ 2.4万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17550011/
关键词：
Physics of Surfaces and Interfaces Atomic and Molecular Physics Catalytic and Chemical Processes

项目摘要

One of the ultimate goals of surface science is to be able to design surfaces with particular catalytic reactivity. This entails a need for an atomic-level understanding of the fundamental principles (elementary processes) underlying the bond-making and bond-breaking at surfaces. The orientation of a molecule incoming on the surface is expected to play an important role in such elementary processes. We have been developing a new machine of ultra-high-vacuum (UHV) compatible oriented-molecular beam line, in order to investigate for initial orientation-effect of an incoming molecule in the surface chemical reactions. The purpose of the present research project is to probe the surface-chemical reaction, especially on Si surfaces, in detail by controlling the molecular orientation of impinging molecules. We report results of a study on the incident-energy and the surface-temperature dependence of the steric effects in the dissociative adsorption of CH_3Cl on a Si(100) surface. The initial sticking probability of CH_3Cl on Si(100) was measured by the King-Wells method. Data presented show that the initial sticking probability for the Cl-end collision is larger at an incident energy of 120 meV than that in the CH_3-end collision. Furthermore, this steric preference is quite sensitive to the kinetic energy and the rotational state of CH_3Cl and the surface temperature. This study shows that the non-equilibrium surface trapping plays a key role in the initial step of the decomposition of CH_3Cl on Si(100). We also introduce the on-going experiments using another new apparatus equipped with the oriented-molecular beam line and the reaction chamber for X-ray photo-emission spectroscopy. In the reaction of oriented NO molecules with Si(111), we found that a N-end collision is more effective in the dissociative adsorption than O-end collision. In addition, we also elucidate the oxide-formation processes on Cu surfaces with oxygen molecular beam.

表面科学的最终目标之一是能够设计具有特定催化反应性的表面。这就需要从原子水平上理解表面成键和断裂的基本原理（基本过程）。预计进入表面的分子的取向在这样的基本过程中起重要作用。为了研究表面化学反应中入射分子的初始取向效应，我们研制了一台超高真空兼容定向分子束线装置。本研究项目的目的是通过控制撞击分子的分子取向来详细探测表面化学反应，特别是在Si表面上。本文研究了CH_3Cl在Si（100）表面上解离吸附的空间位阻效应与入射能和表面温度的关系。用King-Wells方法测量了CH_3Cl在Si（100）表面的初始粘附几率。结果表明，在入射能量为120 meV时，Cl-端碰撞的初始粘附几率比CH_3-端碰撞的初始粘附几率大.此外，这种空间选择性对CH_3Cl分子的动能、转动态和表面温度十分敏感。研究表明，非平衡表面陷阱在CH_3Cl在Si（100）上分解的初始阶段起着关键作用。我们还介绍了正在进行的实验，使用另一种新的装置配备了定向分子束线和反应室的X射线光电子能谱。在取向的NO分子与Si（111）的反应中，发现N端碰撞比O端碰撞更有效地解离吸附。此外，我们还阐明了氧分子束在铜表面氧化物的形成过程。