绝缘表面的共价二聚化机理

发布时间：2018-04-27 16:08

本文选题：绝缘体表面 + 表面合成　；参考：《武汉大学》2017年硕士论文

【摘要】：结合密度泛函原理和高分辨原子力显微镜实验,研究了有机物在绝缘表面上的反应机理。这个研究主要是关于有机分子对碘苯甲酸(IBA)在绝缘的方解石表面(104)上的共价二聚化反应。当系统退火温度达到580K时,在表面上发现了由共价键形成的一维二聚体链。这些二聚体链在表面上有单一取向,是由一系列复杂的反应过程得到的,包括非常难发生的双脱卤反应,以及随后发生的二聚化反应。首先,主要关注双脱卤反应和二聚化过程,运用微调弹性带方法(NEB),分析了一系列可能的反应过程,这些过程包括一个分子和两个分子在表面上的脱卤反应。随后分别研究了这两种情况下促使有机分子在方解石表面上发生反应的关键条件。最后,通过分析两个相关的反应过程,确定了绝缘体表面确实对有机物的共价合成反应起到了一个积极的催化作用:一种是单个有机分子在表面上独自发生反应,彼此之间没有影响,在脱卤反应发生的过程中,表面对分子发生了化学吸附作用;第二种是一个高度非平凡的放热反应过程,在这个反应过程中两个碘原子通过共同协作的方式降低了每个碘原子单独从分子上脱离所需要的能量。与其他的反应方式相比较,这两个反应过程都极大的降低了共价合成反应所需要的能量。知道了绝缘表面上共价合成的反应机理,表明在研究中可以利用共价结构化学键的稳定性,以及它们容易在绝缘体表面上电子解耦的特性,很好的实现对合成物的可控反应。这个研究在纳米和分子电子学中有非常重要的潜在应用价值。
[Abstract]:Based on density functional principle and high resolution atomic force microscope (AFM), the reaction mechanism of organic compounds on insulating surface was studied. This study is mainly concerned with the covalent dimerization of organic molecule p-iobenzoate (IBA) on the surface of insulating calcite (104). When the annealing temperature reaches 580K, a one-dimensional dimer chain formed by covalent bonds is found on the surface. These dimer chains have a single orientation on the surface and are obtained from a series of complex reaction processes, including the dihalogenation reaction, which is very difficult to occur, and the subsequent dimerization reaction. Firstly, a series of possible reaction processes, including one molecule and two molecules on the surface, have been analyzed by using the elastic band method of fine tuning, focusing on the double dehalogenation reaction and dimerization process. The key conditions for the reaction of organic molecules on calcite surface were studied. Finally, through the analysis of two related reaction processes, it is determined that the insulator surface does play a positive catalytic role in the covalent synthesis of organic compounds: one is that a single organic molecule reacts on the surface alone. There is no influence on each other. In the process of dehalogenation, chemisorption occurs on the surface of the molecule; the second is a highly nontrivial exothermic process. In this process, two iodine atoms reduce the energy needed to separate each iodine atom from the molecule by working together. Compared with other reactions, these two reactions greatly reduced the energy required for covalent synthesis. The reaction mechanism of covalent synthesis on insulating surface is known. It shows that the stability of covalent structural chemical bonds and their characteristics of electronic decoupling on insulator surface can be used in the study. This study has important potential applications in nanoelectronics and molecular electronics.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O485

【相似文献】