Probing electronic superexchange coupling at isolated poly-p-phenylene molecules.
Probing electronic superexchange coupling at isolated poly-p-phenylene molecules.
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DOI：
10.1021/ja102415f
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发表时间：
2010-05
影响因子：
15
通讯作者：
Weihua Wang;Shiyong Wang;Xiuyuan Li;J. Collin;Jun Liu;P. Liu;N. Lin
中科院分区：
文献类型：
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作者：
Weihua Wang;Shiyong Wang;Xiuyuan Li;J. Collin;Jun Liu;P. Liu;N. Lin
利用扫描隧道显微镜/光谱技术研究了聚对苯撑分子线在低温下的超交换耦合。通过测量分子碎片轨道对称和反对称二聚化所构成的分子态之间的能量分裂来表征耦合强度。结果证实了理论预测的单分子水平上的超交换耦合的指数衰减行为。得到的衰减常数为0.10 +/- 0.02 A（-1）。由于扫描隧道显微镜的高空间分辨率，分子的内部状态（例如，分子构象）以及外部状态（例如，与外来原子或分子的相互作用）的原子精度阐明的同时，表征超交换耦合。该方法提供了一种新的方法来量化分子内电荷转移是如何受到分子构象和与周围环境的相互作用的影响。
Superexchange coupling in poly-p-phenylene molecular wires was probed using scanning tunneling microscopy/spectroscopy at cryogenic temperatures. The coupling strength was characterized by measuring the energy splitting between the molecular states constructed by symmetric and antisymmetric dimerization of molecular fragments' orbitals. The results confirm the theoretically predicted exponential decay behavior of the superexchange coupling on a single-molecule level. A decay constant of 0.10 +/- 0.02 A(-1) was obtained. Owing to the high spatial resolution of scanning tunneling microscopy, the molecules' internal states (e.g., molecular conformation) as well as external states (e.g., interaction with foreign atoms or molecules) were elucidated with atomic precision at the mean time of characterizing the superexchange coupling. This method provides a new approach to quantify how intramolecular charge transfer is influenced by molecular conformation and interaction with the surroundings.