Kaneko Satoshi, Takahashi Ryoji, Fujii Shintaro, Nishino Tomoaki, Kiguchi Manabu
Department of Chemistry, Graduate School of Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan.
Phys Chem Chem Phys. 2017 Apr 12;19(15):9843-9848. doi: 10.1039/c6cp08862g.
The formation process and atomic structures were investigated for single pyrazine molecular junctions sandwiched by three different Au, Ag, and Cu electrodes using a mechanically controllable break junction technique in ultrahigh vacuum conditions at 300 K. We demonstrated that the formation process of the single-molecule junction crucially depended on the choice of the metal electrodes. While single-molecule junction showing two distinct conductance states were found for the Au electrodes, only the single conductance state was evident for the Ag electrodes, and there was no junction formation for the Cu electrodes. These results suggested that metal-molecule interaction dominates the formation process and probability of the single-molecule junction. In addition to the metal-molecule interaction, temperature affected the formation process of the single-molecule junction. The single pyrazine molecular junction formed between Au electrodes exhibited significant temperature dependence where the junction-formation probability was about 8% at 300 K, while there was no junction-formation at 100 K. Instead of the junction formation, an Au atomic wire was formed at the low temperature. This study provides insight into the tuning of the junction-forming process for single-molecule junctions, which is needed to construct device structures on a single molecule scale.
在300K的超高真空条件下，使用机械可控断裂结技术研究了由三种不同的金、银和铜电极夹着的单个吡嗪分子结的形成过程和原子结构。我们证明了单分子结的形成过程关键取决于金属电极的选择。对于金电极，发现单分子结呈现出两种不同的电导状态，而对于银电极，仅单电导状态明显，并且对于铜电极没有结形成。这些结果表明金属-分子相互作用主导了单分子结的形成过程和概率。除了金属-分子相互作用外，温度也影响单分子结的形成过程。在金电极之间形成的单个吡嗪分子结表现出显著的温度依赖性，其中在300K时结形成概率约为8%，而在100K时没有结形成。在低温下没有形成结，而是形成了一条金原子线。这项研究为单分子结的结形成过程的调控提供了见解，这对于在单分子尺度上构建器件结构是必要的。
