Investigations and Control of Electronic Properties in a Small Number of Molecules

甲基替代寡肽五聚氰胺（DM 5 T）的单聚膜的表面结构和电子性质，使用带有电操作探针的原子力显微镜（AFM）进行了研究。这部电影是由真空沉积在金属基底上准备的。AFM观测揭示了分子被安排在其分子轴上，使其相对于底层的分子轴。local current vs. voltage curves obtained on the film were nonlinear and nonsymmetric with respect to the polarity of the voltage。这部电影的抵抗力约为100Ω厘米，但它在大块材料中比它小一百倍。这是值得注意的，因为当地的电气状况与大宗实验的情况相比得很好。在补充中，表面潜力是由Kelivin Force显微镜（KFM）测量的。这部电影比Pt Substrate有更大的潜力，什么是指示任何电荷从薄膜转移到基底或诱导的分流到薄膜表面的存在？三醇分子也被扫描隧道显微镜（STM）中的高分辨率成像揭示了八醇SAMs是由六格地包装在Au上的分子（111）surface and that the D83 D8x D83 D8and c （4 x2） reconstructed structed were formed。On the other hand， octanedithiol molecules having thiol group at both end were arranged eptaxially with their molecular axes parallel to the substrate。Furthermore，使用STM进行的本地I/V测量显示了在八烯基SAMs上的I/V曲线是非线性的。当样本被积极混淆时，当I/V的特征学被Octanedithiol SAM展示了一个对称性特征。该结果提出了一项结果，即当前是受分子双极影响的当地电场影响。

The surface structures and the electronic properties of monolayer films of methyl-substituted oligothiophene pentamer (DM5T) were investigated using atomic force microscopy (AFM) with an electrically conducting probe. The films were prepared by vacuum deposition onto a metal substrate. AFM observation revealed that the molecules were arranged with their molecular axes perpendicular to the substrate. The local current vs. voltage curves obtained on the film were nonlinear and nonsymmetric with respect to the polarity of the voltage. The resistivity of the film was about 100Ωcm, which was smaller than one hundredth of that in the bulk material. It is noteworthy that the local electrical conduction is much better compared to the case of the bulk experiment. In addition, the surface potential was measured by Kelivin force microscopy (KFM). The film had a higher potential than the Pt substrate, which indicated the existence of either charge transfer from the film to the substrate or induced dipoles toward the film surface.Self-assembled monolayers (SAMs) of the thiol molecules were also investigated by scanning tunneling microscopy (STM) High-resolution imaging of octanethiol SAMs in ultrahigh vacuum environment revealed that the molecules were hexagonally packed on Au (111) surface and that the ィイD83ィエD8xィイD83ィエD8and c (4x2) reconstructed structures were formed. On the other hand, octanedithiol molecules having thiol groups at both ends were arranged eptaxially with their molecular axes parallel to the substrate. Furthermore, local I/V measurements using STM showed that the I/V curves on the octanethiol SAMs were non-linear. The conductivity was higher when the sample was posively biased while the I/V characteristics of the octanedithiol SAMs exhibited a symmetric feature. The results suggested that the current was affected by the local electric field by the molecular dipole.