Lafferentz Leif, Ample Francisco, Yu Hao, Hecht Stefan, Joachim Christian, Grill Leonhard
Physics Department, Freie Universität Berlin, 14195 Berlin, Germany.
Science. 2009 Feb 27;323(5918):1193-7. doi: 10.1126/science.1168255.
The development of electronic devices at the single-molecule scale requires detailed understanding of charge transport through individual molecular wires. To characterize the electrical conductance, it is necessary to vary the length of a single molecular wire, contacted to two electrodes, in a controlled way. Such studies usually determine the conductance of a certain molecular species with one specific length. We measure the conductance and mechanical characteristics of a single polyfluorene wire by pulling it up from a Au(111) surface with the tip of a scanning tunneling microscope, thus continuously changing its length up to more than 20 nanometers. The conductance curves show not only an exponential decay but also characteristic oscillations as one molecular unit after another is detached from the surface during stretching.
单分子尺度电子器件的发展需要详细了解电荷通过单个分子导线的传输情况。为了表征电导率，有必要以可控的方式改变与两个电极相连的单个分子导线的长度。此类研究通常确定具有一种特定长度的某一分子种类的电导率。我们通过用扫描隧道显微镜的针尖将一根聚芴单导线从Au(111)表面拉起，从而连续改变其长度直至超过20纳米，来测量其电导率和机械特性。电导率曲线不仅显示出指数衰减，而且在拉伸过程中随着一个又一个分子单元从表面分离，还呈现出特征性振荡。
