Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
Nano Lett. 2011 Sep 14;11(9):3734-8. doi: 10.1021/nl201777m. Epub 2011 Aug 1.
More than a decade after the first report of single-molecule conductance, it remains a challenging goal to prove the exact nature of the transport through single molecules, including the number of transport channels and the origin of these channels from a molecular orbital point of view. We demonstrate for the archetypical organic molecule, benzenedithiol (BDT), incorporated into a mechanically controllable break junction at low temperature, how this information can be deduced from studies of the elastic and inelastic current contributions. We are able to tune the molecular conformation and thus the transport properties by displacing the nanogap electrodes. We observe stable contacts with low conductance in the order of 10(-3) conductance quanta as well as with high conductance values above ∼0.5 quanta. Our observations show unambiguously that the conductance of BDT is carried by a single transport channel provided by the same molecular level, which is coupled to the metallic electrodes, through the whole conductance range. This makes BDT particularly interesting for applications as a broad range coherent molecular conductor with tunable conductance.
在首次报道单分子电导率的十多年后，证明通过单分子的传输的确切性质仍然是一个具有挑战性的目标，包括传输通道的数量以及从分子轨道角度来看这些通道的来源。我们通过低温下机械可控的断裂结中掺入典型的有机分子苯并二硫醇（BDT），演示了如何从弹性和非弹性电流贡献的研究中推断出这些信息。我们能够通过移动纳米间隙电极来调节分子构象和传输特性。我们观察到具有低电导的稳定接触，其电导约为 10（-3）个电导量子，以及具有高于约 0.5 个量子的高电导值。我们的观察结果明确表明，BDT 的电导由通过相同分子水平与金属电极耦合的单个传输通道提供，在整个电导范围内，该通道提供了单分子电导率。这使得 BDT 特别有趣，因为它可以作为具有可调电导的宽范围相干分子导体应用。
