Innovations in atomic manipulation with the STM: Chlorobenzene on Si(111) 7x7

STM 原子​​操控创新：Si(111) 7x7 上的氯苯

• 批准号: 278588894
• 负责人: Privatdozent Dr. Tillmann Klamroth
• 金额: --
• 依托单位: Lehrstuhl für Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/278588894?language=en
• 关键词: Innovations; atomic; manipulation; STM; Chlorobenzene

Scanning tunnelling microscope (STM) experiments on single molecules represent the extreme limit of nanotechnology. They are also making important contributions to our fundamental understanding of chemical reactions on surfaces, which have immense applications across a spectrum from energy to cancer research. The key insights provided by the STM atomic manipulation approach are to separate out and illuminate the nature of (i) molecular structure and bonding, (ii) electronic excitations, (iii) thermal excitations and (iv) surface sites in molecular reaction pathways. In this project, we aim to develop and apply quantum and classical dynamical approaches to the modelling of STM-induced reactions. Based on open system density matrix theory and first principles cluster calculations, we want to establish a comprehensive dynamical model for the system chlorobenzene on Si(111) 7x7, which has become a paradigm in simple molecular reactions.The chosen system offers a wide range of different STM-induced reactions, for which rich experimental data is available. Nevertheless, only little about the details of the nuclear dynamics is known, due to a notable paucity of theoretical work. Both dissociation of the C-Cl bond and desorption of the whole molecule can be induced by the STM current for bias voltages above certain thresholds (with either polarity). Moreover, the desorption rate is approximately proportional to the tunnelling current, while the dissociation rate scales with the square of the current. Also, several thermally activated channels for dissociation and desorption, which both enhance the current-driven processes, have recently been observed in novel variable temperature experiments.We propose to apply first principles density functional theory calculations, using silicon-clusters to represent the reconstructed surface, to identify important intermediate structures and nuclear coordinates needed for an accurate dynamical description of these reactions. The short lived negative and positive ion resonances, which are believed to drive the STM-induced reactions, will be derived form the electronic structure of these clusters.In close cooperation with the experiments, we will then build dynamical models, which will be tested against experimental data and which will also refine the quantum chemical modelling. Such open system models are capable of describing all of the different experimentally observed reactions. Thus, a detailed understanding of the elementary reaction steps involved in these single molecule experiments can be gained. Over time it is expected that this new understanding will be translated into practical innovations in the control of these reactions and their application.

单分子的扫描隧道显微镜（STM）实验代表了纳米技术的极限。它们还为我们对表面化学反应的基本理解做出了重要贡献，这些反应在从能源到癌症研究的各个领域都有巨大的应用。STM原子操作方法提供的关键见解是分离和阐明（i）分子结构和键合，（ii）电子激发，（iii）热激发和（iv）分子反应途径中的表面位点的性质。 在这个项目中，我们的目标是开发和应用量子和经典动力学方法来模拟STM诱导的反应。基于开放体系密度矩阵理论和第一性原理团簇计算，我们对氯苯在Si（111）7x7上的反应体系建立了一个全面的动力学模型，该体系已成为简单分子反应的范例，并提供了大量的STM诱导反应，这是一个有着丰富实验数据的体系.然而，由于理论工作的显著缺乏，人们对核动力学的细节知之甚少。 C-Cl键的解离和整个分子的解吸都可以由STM电流在高于一定阈值的偏置电压（具有任一极性）下诱导。此外，脱附速率与隧穿电流近似成比例，而解离速率与电流的平方成比例。此外，几个热激活通道的解离和解吸，这两个增强电流驱动的过程，最近已经观察到在新的变温experiments.We建议应用第一性原理密度泛函理论计算，使用硅簇代表重建的表面，以确定重要的中间结构和核坐标需要准确的动力学描述这些反应。短寿命的负离子和正离子共振被认为是STM诱导反应的驱动力，将从这些团簇的电子结构中推导出来。在与实验的密切合作下，我们将建立动力学模型，并将根据实验数据进行测试，这也将完善量子化学模型。这样的开放系统模型能够描述所有不同的实验观察到的反应。因此，可以获得对这些单分子实验中所涉及的基元反应步骤的详细理解。随着时间的推移，预计这种新的理解将转化为控制这些反应及其应用的实际创新。