Fabrication of Metallic Architectures for precise control of energy conversion

在这个项目中，我们制造了结构明确的金属纳米结构，能够在热能、光子、动能和电化学能量之间进行能量转换。特别是，我们集中了以下三个主题。首先是控制金属原子线中的电子传导过程。在由单原子结连接的原子线中，电子的传导特性可以通过外部电化学能量来控制。我们已经成功地控制了能量和自旋选择性电子传导的基础上，在两个电极的结。此外，振动谱的原位测量澄清了小分子在结中的插入过程。第二是光子能量到分子振动能量的转换。为了实现有效的转换，我们将局部增强电场集中在金属纳米结构周围。结构中的电子在具有共振能量的光照射下集体振荡。这导致了结构周围高度增强的电场。通过测量位于结构附近的单个分子的拉曼散射信号，我们发现散射截面比普通拉曼过程增加了10^10的数量级。三是利用金属结构控制分子的扩散能。金属纳米结构的二维阵列已经证明了对分子组装集体流动的整流能力。本项目的研究成果将为未来的纳米器件提供新的分子/电子操纵、整流和检测系统。

In this project, we have fabricated structurally well-defined metallic nano-architectures that are capable of energy conversion among thermal, photon, kinetic, and electro-chemical energies. Especially, we have concentrated three subjects below. First is a controlling of an electron conduction process in a metal atomic wire. In the atomic wire connected by a single atom junction, electron conduction characteristics can be controlled by external electro-chemical energy. We have succeeded in controlling of energy-and spin-selective electron conduction based on the electro-chemical potential at both electrode of the junction. Additionally, an in-situ measurement of vibrational spectrum has clarified the insertion process of a small molecule in the junction. Second is a conversion of photon energy to molecular vibration energy. To realize an effective conversion, we focused locally enhanced electric field around metal nano-architecture. Electrons in the architecture collectively oscillate by a light-irradiation with resonant energy. This causes highly enhanced electric field around the architecture. By measuring a Raman scattering signal from a single molecule situating at a close proximity of the architecture, we have found that the scattering cross-section was increased by the order of 10^10 compared with normal Raman process. Third is a controlling a molecular diffusion energy by using of metallic architecture. Two-dimensional array of metallic nano-architecture has demonstrated rectification ability concerning a collective flow of a molecular assembly. These research results in the present project will offers new molecular/electron manipulation, rectification, and detection systems in a future nano-devices.