Observation of quantum interference in molecular charge transport
Observation of quantum interference in molecular charge transport
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DOI：
10.1038/nnano.2012.37
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发表时间：
2012-05-01
影响因子：
38.3
通讯作者：
van der Molen, Sense Jan
中科院分区：
文献类型：
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作者：
Guedon, Constant M.;Valkenier, Hennie;van der Molen, Sense Jan
当导体的尺寸接近纳米尺度时，量子效应开始占主导地位，并且可以通过直接操纵电子波函数来控制电导。这种控制已在低温下的各种介观装置中得到证明(1-4)，但事实证明很难在较高温度下对波函数进行控制。分子具有典型的能级间距（类似于 eV），远大于 300 K 的热能（类似于 25 meV），因此是此类实验的自然候选者。此前，巨磁阻(5)、近藤效应(6)和电导切换(7-11)等现象已经在单分子中观察到，理论学家预测也应该有可能在分子导体中观察到量子干涉(12-18)，但到目前为止，这种行为的所有证据都是间接的。在这里，我们报告了室温下通过两端分子连接的电荷传输中破坏性量子干涉的观察。我们研究了五种不同的刚性 p 共轭分子线，所有这些分子线都在金表面上形成自组装单层，并发现干扰程度可以通过分子线的简单化学修饰来控制。
As the dimensions of a conductor approach the nanoscale, quantum effects begin to dominate, and it becomes possible to control the conductance through direct manipulation of the electron wavefunction. Such control has been demonstrated in various mesoscopic devices at cryogenic temperatures(1-4), but it has proved to be difficult to exert control over the wavefunction at higher temperatures. Molecules have typical energy level spacings (similar to eV) that are much larger than the thermal energy at 300 K (similar to 25 meV), and are therefore natural candidates for such experiments. Previously, phenomena such as giant magnetoresistance(5), Kondo effects(6) and conductance switching(7-11) have been observed in single molecules, and theorists have predicted that it should also be possible to observe quantum interference in molecular conductors(12-18), but until now all the evidence for such behaviour has been indirect. Here, we report the observation of destructive quantum interference in charge transport through two-terminal molecular junctions at room temperature. We studied five different rigid p-conjugated molecular wires, all of which form self-assembled monolayers on a gold surface, and find that the degree of interference can be controlled by simple chemical modifications of the molecular wire.