The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
Nanoscale. 2009 Oct;1(1):164-70. doi: 10.1039/b9nr00122k. Epub 2009 Sep 2.
Single molecule identification in metal-molecule-metal junctions provides an ultimate probe that opens a new avenue for revolutionary advances in demonstrating single molecule device functions. Inelastic electron tunneling spectroscopy (IETS) is an ultra-sensitive method for probing vibrational characteristics of molecules with atomic resolution. State-of-the-art experiments on the inelastic transport in self-assembled monolayers of organic molecules have demonstrated the utility of the IETS technique to derive structural information concerning molecular conformations and contact configurations. Here we report the vibrational fingerprint of an individual pi-conjugated molecule sandwiched between gold nanoelectrodes. Our strategy combines analyses of single molecule conductance and vibrational spectra exploiting the nanofabricated mechanically-controllable break junction. We performed IETS measurements on 1,4-benzenedithiol and 2,5-dimercapto-1,3,4-thiadiazole to examine chemical discrimination at the single-molecule level. We found distinct IET spectra unique to the test molecules that agreed excellently with the Raman and theoretical spectra in the fingerprint region, and thereby succeeded in electrical identification of single molecule junctions.
在金属-分子-金属结中进行单分子识别为演示单分子器件功能的革命性进展提供了终极探针。非弹性电子隧穿谱（IETS）是一种超灵敏的方法，可在原子分辨率下探测分子的振动特性。在有机分子自组装单层中的非弹性输运的最先进实验已经证明了 IETS 技术对于获得有关分子构象和接触构型的结构信息的实用性。在这里，我们报告了夹在金纳米电极之间的单个π共轭分子的振动指纹。我们的策略结合了利用纳米制造的机械可控断接结进行的单分子电导和振动光谱分析。我们对 1,4-苯二硫醇和 2,5-二巯基-1,3,4-噻二唑进行了 IETS 测量，以在单分子水平上检查化学鉴别。我们发现了独特的 IET 谱，这些谱与测试分子完全一致，在指纹区域与拉曼和理论光谱非常吻合，从而成功地实现了单分子结的电学识别。
