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扫描隧道显微镜在单分子科学中的应用

Application of scanning tunneling microscope in single molecule science

  • 摘要: 单分子科学是一门新兴的交叉科学,在当前的科技发展中具有重要意义.扫描隧道显微镜是研究单分子的一种强有力而独特的工具.文章以作者所在研究组近年来在单分子表征、操控和原型器件设计等方面的研究工作进展为例,概述了扫描隧道显微镜在单分子科学中的应用,重点介绍了以下成果:在硫醇分子自组装单层膜上观测到C60分子的本征笼状结构,并发现了一种新颖的由C60分子取向产生的拓扑序;结合实验图像和理论模拟,确定了单个C60分子在Si(111)-7×7表面的吸附取向;通过对金属富勒烯分子Dy@C82进行空间和能量分辨成像及相关理论模拟,确定了金属原子相对碳笼的位置及分子的取向;利用扫描隧道显微镜针尖对吸附在Au(111)表面的单个CoPc分子操作“分子手术”,以实现其吸附态和自旋态的量子调控;发现了一种由单电子隧穿和C59N分子的特殊能级结构产生的新的整流机制;发现了一种由针尖电子态和CoPc分子中Co原子轨道的空间对称性匹配产生的负微分电阻效应.

     

    Abstract: Single molecule science is a new emerging cross discipline, and is significant in current development of the sciences and technologies. Scanning tunneling microscope (STM) is a powerful and unique technique to research the single molecule. In this review, we will summarize application of STM in single molecular science, with some recent progresses on characterizing, manipulation single molecule and designing related molecular device by our group being introduced as typical examples as follows: the native cage structure of C60 molecule on self -assembled monolayer of alkylthiol was observed, and a new topological order originating from the orientation of C60 molecule was found; by combining the experimental images and theoretical simulations, the orientation of C60molecule on Si(111)-7×7surface was identified; the energy-resolved metal-cage hybrid states of single Dy@C82 molecule were mapped, and then the relative position of the metal atom inside the cage and the molecular orientation was inferred by comparing the experimental results and the theoretical simulations; by performing “molecular operation” to the CoPc molecule on Au(111) surface by using STM tip, the adsorption state and spin state of the CoPc molecule was controlled; based on single electron tunneling effect and special energy structure of C59N molecule, a new mechanism of molecular rectifying was built; a negative differential resistance effect related to local orbital symmetry matching between the Co atom in single CoPc molecule and STM tip was found.

     

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