Chemistry of Pseudo Molecules on Metal Surfaces

本项目设计了一套用于研究金属表面化学反应的扫描隧道显微镜(STM)系统。屋顶上悬挂了一种专为化学反应而设计的特高压吸尘器，使用这四条链来隔离振动噪声。用超高真空扫描隧道显微镜研究了金属表面的吸附和催化过程。金属表面暴露在反应性气体中，表面的金属原子发生化学反应，描述为两个过程，一个是“准化合物的形成”，另一个是“表面上的自组装”。这个新概念已经通过STM对原子过程的洞察得到了证明，它允许我们考虑通过对准化合物进行排序来制造新的表面。根据暴露在O2中的铜(110)表面的原子过程，我们假设在台阶边缘形成(CuO)^*中间体，并在平台上快速扩散以沿[001]方向生长(-CuO-O-)链。假设[CuO]^*可能存在于Cu(110)表面，我们可以预期在Ag(110)表面也会存在相同的[CuO]^*中间体。基于这一思想，我们成功地在Ag(110)表面上得到了一个由有序的(-Cu-O-)链组成的新表面，这些链沿[110]方向生长。Ag(110)表面的(-CuO-)沿[110]方向发生分解，形成(Cu6)6团簇。通过将(-Ag-O-)和(Ag2N)准化合物结合在一起，我们可以在Ag(110)表面形成新的图案。如果用紫外光照射这个表面，(-Ag-O-)链被照明选择性地漂白。此外，还开发了一种新的原子技术--“原子涂色”。这些结果表明，通过化学反应和/或光化学反应可以制作原子尺度的表面。

In this project, an STM (scanning tunneling microscopy) system for studying the chemical reaction of metal surfaces was designed. A special UHV cahmber designed for chemical reaction was hung from the roof by using the four chains to isolate from the vibrational noise. Metal surfaces during adsorption and catalysis were studied by using this UHV-STM.Wen metal surfaces are exposed to reactive gases, metal atoms of the surface undergo chemical reaction, wich is described by the following two processes, one is "the formation of quasl-compounds" and the other is "thelr self-assembly on the surface". This new concept has been proved by getting insight of the atomic processes with the STM,which allows us to consider the fabrication of new surfaces by ordering thequasi-compounds. From the atomic processes of Cu (110) surface exposed to O_2, we assumed the formation of an intermediate of (CuO)^* at the step edges and and their rapid diffusion over the terrace to grow (-Cu-O-) chains along the [001] direction. Providing that the [CuO]^* may exist on the Cu (110) surface, we could expect the existence of the same [CuO]^* intermediates on Ag (110) surface. Based on this idea, we succeeded in gettinga new surface which is composed of an ordered (-Cu-O-) chains on Ag (110) surface, where the chains grow in the [110] direction. The (-Cu-O-) on Ag (110) surface undergoes the decomposition along the [110] direction to form (Cu)_6 cluser dots. By combining the (-Ag-O-) and (Ag_2N) quasi-compounds, we can make a new pattern on Ag (110) surface. If this surface is illuminated with a UV-light, the (-Ag-O-) chains are selectivly bleached by the illumination. In addition, a new atom technology named as "atom palnting" has been developed. These results suggest a potentiality for the atomic scale surface fabrication by the chemical and/or photochemical reactions.