Chemistry of Pseudo Molecules on Metal Surfaces

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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.