【作者】 董晨初；

【导师】 王泽新；

【作者基本信息】 山东师范大学 ， 物理化学， 2005， 硕士

【摘要】 气念分子与表面相互作用动力学闩益引起越来越多的化学家和物理学家的兴趣。无 论是多相催化还是胶体化学催化反应,都涉及到反应物之间及反应物与催化剂表面的相 互作用。因而,从理论上系统地研究原子、分子之间以及它们与催化剂表面,尤其是与 表面活性部位之间的相互作用是十分必要的。 本论文的主要内容如下: 第一章主要是详细介绍了本论文研究所用到的基本理论和低指数表面簇合物模型。 第二章中利用我们提出的5参数Morse势方法,重点对O在Pt低指数面及台阶面体系的吸附和扩散进行了全面系统的研究。 第三章中利用构造的气态双原子分子与表面相互作用势函数-推广的LEPS势对O₂-Pt体系进行了细致的研究。 本论文的主要研究成果: 1.O-Pt低指数面吸附体系。振动频率是比较容易测得的实验信息,而且是确定吸附位 和吸附念的最重要的临界性质。但实验上往往是在不同的条件下进行,得到的大都是片 断信息,对于振动频率的归属问题也往往相互矛盾。计算结果表明.氧原子在Pt（100）面 上只存在四重吸附念。在（111）而上,氧原子吸附于三重洞位,获得的乖亢振动频率 58.10meV可看作足氧原子在Pt（111）面吸附的三重念的特征频率。在缺行重构的（110）面 上,氧原子仍吸附于三重位,随着覆盖度的增加还会嵌切吸附于长桥位;通过分析三重 态指纹性质的遗传和遗变,确认实验观察到的59.4.9meV和40.90meV损失谱分别为氧 原子在三重位和长桥位吸附态的表面垂直振动。不但重现了实验上测得的特征振动频 率,而且给予了相应吸附位和吸附几何的确认。 该论文已在物理化学学报,2004,20（9）,1123～1128上发表。2. O-Pt台阶面体系。我们研究了两类台阶面。在O-Pt（s）[n（111）×（100）]台阶面体系中,重点研究了O/Pt（311）、O/Pt（221）和O/Pt（533）等3个体系。结论表明:氧原子稳定吸附在台阶（step）下的四重位,对应稳定吸附态β、:平台（terrace）上稚近四重位的三重吸附态被湮灭,其它三重位对应吸附态β₁:而且平台的长度对四重吸附念的性质影响较大。在O-Pt（s）[n（111）×（111）]体系中,详细研究了O/Pt（331）、O/Pt（221）和O/Pt（553）体系。结果更多还原

【Abstract】 The dynamics of gas-solid surface interaction is arousing more and more interest in the community of physicists and chemists. Whether multi-phase catalysis or colloid catalyzed interaction is relating to the interaction between reactants as well as between reactant and catalyzer surface. Therefore, the systemic study on the interaction between atom, molecule and catalyzer surface, especially the interaction with active sites in theory is necessary.The main content in this paper is as follows:In chapter 1. the elementary theory for calculation in this paper and the low- index surface cluster models are given.The adsorption and diffusion for O-Pt low-index surface and stepped surface systems entirely are investigated by constructing atom-solid surface interaction potential named five parameters Morse potential (5-MP for short) in chapter 2.The analytical potential of gaseous diatom molecule interaction system, i.e. extended LEPS potential has been constructed. And C2-Pt systems is studied in chapter 3.The main research fruit in this work is as follows:1. The adsorption system of O atom on the Pt low-index surfaces. The vibration frequencies are easy to measure in experiments, and are the most important critical characteritics to ascertain the adsorption sites and states. However, the experiments are made under different conditions, and mostly obtain bitty information. Moreover, the problem on the attribution of frequencies is usually inconsistent. The theoretical calculated results show that oxygen atom can only adsorb in the four-fold hollow site on Pt (100). On (111) surface, there exists adsorption state of oxygen atom in the three-fold hollow site, which produce vertical vibrational frequency 58.10meV considering as special frequency for the three-fold adsorption state of O-Pt(111) system. O adsorbs in the three-fold hollow site and the long-bridge site on the (110) missing-row reconstruction surface. We ulteriorly analyze heredity and variation of vibrational fingerprint properties of three-hold state on Pt(111).Then we can confirm that experimental data about 59.49meV and 40.90meV on the (110) missing-row reconstruction surface belong to vertical vibrations of adsorption states, which are produced by oxygen atom on three-hold hollow site and long-bridge site, respectively. Calculation results not only reproduced the vibration frequencies but also ascertained adsorption sites and states.This paper has been published on Acta Phys.-Chim.Sin., 2004, 20(9), 1123~1128.2. The adsorption systems of O atom on Pt stepped surface. We study two kinds of stepped surfaces. The theoretical calculated results about O/Pt(s)-[n(111)×(100)] systems mainly including O-Pt(311), O-Pt(211) and O-Pt(533) systems draw some conclusions. The four-fold site behind a (111) step that a oxygen atom binds in corresponds to the most stable statenamed β2 -state. And the three-fold state near the four-fold site on a (111) terrace is annihilated,then the other three-fold sites correspond to adsorption states named β1-state. In addition thelength of the (111) terrace has a bit of the effect on the four-fold state. Moreover, we investigate the adsorption properties of a series of O-Pt(s)[n(111)×(111)] systems which emphasized O/Pt(331),O/Pt(221) and O/Pt(553) systems. And our results suggest that O atomadsorbs stably on the step. There are two types of atomic states (β1 and β2) in the adsorbedsystems, corresponding to the three-fold states and four-fold long-bridged state on the step respectively. Comparing with the former kind of stepped surface systems, the lengths of (111) terrace affect weakly the properties of all critical points in this kind of systems. The researches about O adsorbing on Pt stepped surface systems carried out by 5-MP method can make up for the experimental deficient information and confirm the adsorption sites which can be not ascertained with experimental methods. The calculation results approve of the experimental view that the step on the surface is the active position in the catalyzed reaction.The one article has been published on Acta Phys.-Chim.Sin., 2004. 20(12), 1445~1450.The other one has been accepted by Chinese Journal of Structural Chemistry and finalized a manuscript.3. The system of O2 on the Pt low-index surfaces. The extended LEPS of O2-Pt single crystal plane systems is constructed by means of 5-MP(the 5-parameter Morse potential). Bothadsorption and dissociation of O2 on Pt low index surfaces mainly including (111) and (110) reconstruction surfaces are investigated with extended LEPS in detail. We obtain all critical characteristics of the system, such as adsorption geometry, binding energy, eigenvalues for vibration, etc. Our calculated results suggest the dissociation of O2 on Pt(111) surface is difficult and surperoxo-like state exists likely. Meanwhile, we use the conceptions of the molecular dissociation limit and the surface dissociation distance to analyze the dissociation mechanisms of O2 on the two Pt surfaces. Moreover, the vibration frequencies of 860cm-1, 930cm-1, 1250cm-1 produced by O2 adsorbing on Pt(110) reconstruction surface are assigned logically on the basis of the molecular fingerprint properties.The paper has been contributed to Chinese Journal of Catalysis.更多还原