【作者】 于海燕；

【导师】 刁兆玉；

【作者基本信息】 山东师范大学 ， 物理化学， 2010， 硕士

【摘要】 气态原子、分子与过渡金属表面的相互作用是多相催化、气体腐蚀以及晶体生长等领域研究中的一个重要课题。尤其是近年来,伴随着化学工业中异相催化的迅猛发展,气-固表面相互作用动力学引起化学家和物理学家的极大兴趣。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以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、分子与催化剂表面,尤其是与催化剂表面活性部位之间的相互作用是十分必要的。本论文选取了一些具有典型意义的原子和双原子分子通过5-参数Morse势和改进推广的LEPS势方法研究了原子、分子在过渡金属平坦和缺陷表面的吸附扩散动力学行为。本论文的内容简述如下:第一章简要介绍了气固表面相互作用的研究意义、研究现状、研究方法,并详细介绍了本论文研究所要用到的基本理论方法和表面簇合物模型。第二章应用5-参数Morse势（简称5-MP）分别对N-Ru、O-Ag表面体系的吸附和扩散进行了全面系统的研究。第三章在5-MP的基础上利用改进推广的LEPS势对NO-Ru低指数面及CO- Pd（211）（311）台阶面吸附体系进行了详细的研究。本论文的主要成果:1. N-Ru体系。虽然此前人们对N-Ru体系进行了大量的研究,且主要是实验研究,但只获得了表面吸附微观动力学的片段信息。例如:对于（1 121）台阶面,实验上测得了很多能量损失谱,但对其归属,目前仍没有明确的论断。理论计算结果认为:N原子在金属钌表面上的吸附倾向于三重位;在（1 010）低指数面上不存在子表面吸附态;在开放的（1 121）台阶面上存在6种不等价吸附态,并且可分为子表面吸附、次表面（facet）吸附和表面吸附三类。理论计算结果几乎都重现并解释了EELS实验测得的损失谱峰,并且指派了相应吸附位和吸附几何构型,同时还预测了其它振动频率的存在。该论文已发表在Chemical Research in Chinese University 2009年9月5期25卷。2. O-Ag体系。利用5-参数Morse势方法（简称5-MP）,对O-Ag（100）,（110）,（111）平坦表面体系进行了全面系统的研究。为人们更加全面详细地了解这一重要体系提供了的帮助。对于O原子在Ag（111）面上的吸附,实验上测得的低频振动30meV,较为反常。但通过我们的计算结果,可预言这是由于Ag（111）面上的稀疏台阶对O原子吸附态的影响所致。关于O-Ag（211）,（997）,（410）台阶缺陷表面体系的研究也取得了较好的计算结果。3. NO-Ru低指数面体系。应用原子和表面簇合物相互作用的5-参数Morse势及推广的LEPS势进行了较为全面、系统的研究,获得了结合能、键长、吸附高度和振动频率等全部临界点性质,且与实验结果吻合较好。理论计算结果认为:NO在Ru（0001）面上存在多种分子吸附态,分别是顶位吸附态、桥位吸附态、三重位的垂直吸附态以及质心在桥位的平行吸附态,对应的频率分别为1732 cm^-1,1587 cm^-1,1451（1459） cm^-1和672 cm^-1。对于实验上出现的1130 cm^-1的特殊振动频率,本文认为该频率是由NO分子缔合产生的。在Ru （1 010）面,NO同样存在多种分子吸附态。但从计算结果来看,NO在此面不存在平行的分子吸附态。4.对于CO-Pd台阶面体系,重点研究了CO/Pd（211）和CO/Pd（311）两个体系。计算结果表明,在低覆盖度下,CO分子都是趋向吸附在（211）、（311）台阶面的三重位,基本上遗传了CO-Pd（111）三重吸附态的临界点性质。随着覆盖度的增加,又会垂直吸附在（100）台阶的二重桥位上,与CO在Pd（100）平面桥位吸附时的临界点性质都非常接近。但由于（211）、（311）两个面中（111）台面的长度不同,因此也存在不同之处。CO分子在（211）面上存在稳定的高配位吸附位,但在（311）面上没有稳定的高配位吸附位。更多还原

【Abstract】 The dynamics of gas-solid surface interaction is arousing more and more interest in the community of chemists and physicists. Whether colloid catalyzed interaction or multi-phase catalysis is relating to the interaction 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. Some representative atoms and molecules are selected to study the kinetic behavior of adsorption and diffusion on the flat and defective surfaces by employing five-parameter Morse potential and improved extended LEPS potential in this work.The main content in this paper is as follows:Chapter 1: the significance, status quo and methods of the investigation in gas-solid surfaces interaction are expatiated. On the other hand the theory methods and cluster modes used in this dissertation are introduced in detail.Chapter 2: N-Ru system and O-Ag system are studied by using 5-parameter Morse potential （5-MP） method.Chapter 3: The characteristics of adsorption sites and state for NO molecule on Ru low-index surfaces and CO-Pd （211）,（311）stepped surfaces are investigated by extended LEPS method.The main production of this paper:1. N-Ru system. Although the N-Ru system has been studied by many methods, especially experimental methods, only limited information was obtained. There are even more puzzles needed to be explained. For example, a variety of losses were observed for N atom on Ru （1 121） surface, but how to assign these losses? Calculated results demonstrate that the N atom has the tendency to adsorb at three-fold sites. There is no subsurface states for N atom on Ru （1 010） surface and there exist 6 stable adsorption sites for N atom on Ru （1 121） stepped surface which can be classified into 3 types: the on-surface adsorption states, the facet adsorption states and the subsurface states. And other calculated results are in good accord with HREELS experiments. Meanwhile, we predict that there exist some other vibrational frequencies.This paper has been published on Chemical Research in Chinese University, 2009, Vol.25, No.5, 705⁷10.2. O-Ag system. we dealt with the O-Ag（100）,（110）,（111） plane surface systems comprehensively, using the 5-MP method, which make it possible for people to understand this important system detailedly and completely. With regard to the adsorption of O atom on the Ag （111） surface, our calculation results suggest that the abnormally low vibration of 27.3, 30meV of EELS experimental results should be resulted by the effect of the sparse steps to the nearest neighbouring hollow site on the Ag （111） terrace. The investigation to O atom adsorbed on the Ag （211）, （997）, （410） step surfaces also gained better calculation results.3. N-Ru system. The extended LEPS of NO-Ru system are constructed by means of 5-MP. All critical characteristics of the system we obtained, such as adsorption geometry, binding energy, eigenvalues for vibration, etc. are in good agreement with the experimental results. There exist several adsorption states for NO adsorption on Ru（0001） surface:T, B, H and H-B-H sites, and the vibrational frequencies are 1732cm^-1,1587 cm^-1,1451（1459） cm^-1和672 cm^-1 respectively. The unusual vibrational frequency of 1130 cm^-1 is atributed to hyponitrite form. For NO adsorption on Ru （1 010）surface, there also exist several adsorption states, but parallel adsorption state is not found.4. For the adsorption systems of CO on Pd stepped surfaces, We study mainly CO-Pd（211） and CO-Pd（311） systems. The results show: there exist common characters of CO molecule adsorption on these two surfaces. At low coverage, CO molecule will perpendicularly adsorb in three-fold hollow site of the （111） terrace and has a tilt angle with respect to the surface normal. The critical characters inherit the characters of CO molecule adsorbed in three-fold hollow site of （111） original surface. When the coverage is increasing, two-fold bridge sites of （100） step are occupied. The critical characters inherit the characters of CO molecule adsorbed in two-fold bridge sites of （100） original surface. Considering the different length of （111） terrace, there exist some different characteristics of （211） and （311） stepped surfaces. A number of new sites are exposed on the boundary regions between the two types of surface, for example H5 of （211）and H4 of （311） surface. When the coverage is up, CO will inside in H5 of （211） surface, but the H4 of （311） surface will not be a stable adsorption state.更多还原