在单分子连接处测量依赖连接器的键断裂力
Michael Frei1, Sriharsha V Aradhya, Mark S Hybertsen
1Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA.
Journal of the American Chemical Society
|February 18, 2012
概括
我们测量了不同化学环节组的单分子连接电导和断裂力. 由于强大的黄金-硫黄键,醇链组表现出独特的行为,但仍在低于黄金-黄金键的力量下破裂.
科学领域:
- 分子电子学分子电子学
- 纳米技术纳米技术
- 表面科学是一门科学.
背景情况:
- 了解单分子结合特性对于分子电子学至关重要.
- 连接组的选择显著影响了连接点的稳定性和导电性.
- 原子力显微镜 (AFM) 是探测分子结合的一个关键技术.
研究的目的:
- 研究链接组化学与单分子结合的机械和电气性能之间的关系.
- 为了比较不同结合组 (胺基,甲基硫化物,二,醇) 的破裂力和导电特征与金电极.
- 阐明电极-分子相互作用的作用,特别是强共价键,在结点行为上的作用.
主要方法:
- 使用修改过的导电原子力显微镜 (CAFM) 同时测量导电量和破裂力.
- 使用具有四个不同的终端连接组的烯制造的单分子结.
- 在连接形成和断裂过程中分析了导电痕迹和力距离曲线.
主要成果:
- 带有氨基,甲基硫化物和二酸连接器的连接处表现出明显的导电性,并且在比单原子黄金接触器低的力下破裂.
- 硫醇终结基形成了强大的金硫键,导致电极结构重组和显著的导电量变化.
- 尽管有强大的Au-S结合和电极破坏,但在平均低于原始单原子黄金接触力的力量下,醇结合的连接点也破裂了.
结论:
- 连接组的结合强度和机制极大地影响单分子连接的稳定性和导电性.
- 强大的共价相互作用,如Au-S键,可以诱导电极的修改,改变连接属性.
- 分子结口的破裂力通常低于赤裸金属接触的破裂力,无论结合组的结合强度如何.
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