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First Principle Studies on Oxidation of Aluminum 13 Anion Cluster and Hydrogen Desorption from Hydrogenated Silicon (100) Surface.

机译：铝13阴离子簇的氧化和氢从氢化硅（100）表面脱附的第一原理研究。

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摘要

Reactions on solid surfaces play a crucial role in many technologically important areas such as corrosion, adhesion, synthesis of new materials and heterogeneous catalysis. Theoretical studies on chemical reactions at surfaces can provide much useful information to understand and control these chemical processes. The present project is devoted to explore chemical reactions occurred on the aluminum cluster of Al13- and on the Si(100) surface by first principle calculations, using Gaussian 03 and Vienna Ab Initio Simulation Package (VASP).;The Al13-+HX reactions, with HX being either HCl or HI, are explored by first principle calculations and two importance dynamic factors are identified. Firstly, there was a barrier to the dissociative adsorption of FIX on the surface of an Al13- cluster, which involved charge transfer from Al13-. Secondly, the H atom could be bonded to the cluster in multiple ways, similar to the top, bridge and hollow adsorption sites on Al(111) surface. With a large amount of energy (>40 kcal/mol) deposited during the formation of Al13 -HX-, the H atom could easily migrate among these sites, similar to the diffusion of H on metal surfaces. The two dynamic factors were therefore important considerations in the formation and dissociation of Al 13-HX- And moreover, these dynamic factors make Al13- a fascinating model to probe the dynamic aspect of surface reactions, which should be an important consideration in the reactivity of other metal clusters.;Hydrogen desorption mechanisms on hydrogenated silicon surface such as H/Si(1 00)-1x1, H/Si(l00)-2xl and H/Si(100)-3x1 surfaces have been explored by theoretical calculations with slab models. Similar desorption mechanisms have been identified for three hydrogenated surfaces and the calculated barriers were in agreement with experimental values. More interestingly, a common bridge structure has been identified as an intermediate. Its unique electronic structure is analyzed in detail. The identification of such a structure provides an alternative account for previous experimental results on STM tip-induced desorption.;Metal atom clusters are nanoscale intermediates between metal atoms and the bulk metal. Al13- can be regarded as a cluster model for Al(111) due to its special electronic and geometric structures. The reaction between Al13- and O2 was explored by various DFT methods such as BLYP, PW91, PBE, B3LYP and BHHLYP and post-HF methods such as CCSD and QCISD(T). The calculation results demonstrated that the reaction was exothermic and thermodynamically quite favorable, and the reason for the stability of Al13- towards oxygen exposure was kinetic, due to the presence of a reaction barrier. True to the expectation of Al13- as a molecular model for the Al surface, the identification of this barrier resolved a long standing puzzle in the initial chemisorption of O2 on Al(111): a barrier was identified in experiment but not in any theoretical calculations on the ground state potential surface.
机译：固体表面上的反应在许多技术上重要的领域中起着至关重要的作用，例如腐蚀，附着力，新材料的合成和非均相催化。对表面化学反应的理论研究可以提供许多有用的信息，以了解和控制这些化学过程。本项目致力于使用高斯03和Vienna Ab Initio模拟程序包（VASP）通过第一原理计算来探索在Al13-的铝团簇和Si（100）表面上发生的化学反应; Al13- + HX反应通过第一原理计算探索了HX为HCl或HI的情况，并确定了两个重要的动态因素。首先，对于FIX在Al13-团簇表面的解离吸附有一个障碍，这涉及从Al13-转移电荷。其次，氢原子可以多种方式键合到团簇上，类似于Al（111）表面的顶部，桥梁和中空吸附位。在Al13 -HX-的形成过程中沉积大量能量（> 40 kcal / mol），H原子很容易在这些位点之间迁移，类似于H在金属表面的扩散。因此，这两个动力学因素是Al 13-HX的形成和解离的重要考虑因素，而且，这些动力学因素使Al13-成为探讨表面反应动力学方面的引人入胜的模型，这应该是Al13-HX反应性的重要考虑因素。通过板的理论计算，探索了氢化硅表面上的氢解吸机理，例如H / Si（1 00）-1x1，H / Si（100）-2xl和H / Si（100）-3x1表面楷模。对于三个氢化表面，已经确定了相似的解吸机理，并且所计算的势垒与实验值一致。更有趣的是，已将常见的桥梁结构识别为中间结构。详细分析了其独特的电子结构。这种结构的鉴定为先前关于STM尖端诱导的解吸的实验结果提供了另一种解释。金属原子团簇是金属原子和大块金属之间的纳米级中间体。 Al13-由于其特殊的电子和几何结构而可以被视为Al（111）的簇模型。通过各种DFT方法（例如BLYP，PW91，PBE，B3LYP和BHHLYP）和HF后方法（例如CCSD和QCISD（T））探索Al13-和O2之间的反应。计算结果表明，该反应是放热的，并且在热力学上是非常有利的，并且由于存在反应障碍，Al13-对氧气暴露的稳定性的原因是动力学的。符合Al13-作为Al表面分子模型的预期，此障碍的确定解决了O2在Al（111）上初始化学吸附的长期难题：在实验中确定了障碍，但未在任何理论计算中确定在基态电位表面上。

著录项

  • 作者

    Yuan, Qinghong.;

  • 作者单位

    The Chinese University of Hong Kong (Hong Kong).;

  • 授予单位 The Chinese University of Hong Kong (Hong Kong).;
  • 学科 Chemistry Physical.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 122 p.
  • 总页数 122
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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