Development of specular-reflecting wall by super-flattening process and its appliation to vacuum technology

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The primaryaim of this project is to realize a specular reflecting wall for thermal energy gasmolecules The key technology to the processing of the specular reflecting wall is thought to be super-flattening of practical wall materials and adsorbate-free surface cleaning in ultrahigh vacuum condition.In the proiect, we divided our activity into three sub-themes(1) Development of flat surfaces in atomic scale(2) Measurement of deviations from diffuse scattering by using resonant enhanced multi-photon ionization technique (REMPI)(3) Direct measurement of angular distribution of scattered molecules by molecular beam technique.(1)Development of flat surfaces in atomic scaleWe mainly studied the flattening process of polished Pt surfaces. The flattening of rough surfaces after ion bombardment for the cleaing was studied by scanning tunneling microscope. The condition for the formation of monatomic-height terrace was determined.(2) Measurement of deviations from diffuse scattering by using re … More sonant multi-photon ionization techniqueWe applied resonant multiphoton ionization technique to the detection of hydrogen molecules which are the major constituent in ultrahigh vacuum environment. The ultraviolet light was generated by frequency doubling of Nd-YAG laser followed by sum-frequency generation in BBO crystal. The minimum detection limit was less than 1*10^<-6> Pa. As a proof for the specular reflection, we tried to measure angular distributions of hydrogen molecules through a Pt capillary. At present, the measurement was unsuccessful mainly due to the lack of sufficient pumping speeds in the vacuum system. The refinement of the vacuum pumps are going to be made.(3) Direct measurement of angular distribution of scattered molecules by molecular beam techniqueA molecular beam apparatus was developed in Tsukuba University and applied to the angular distribution measurement of modified metal surfaces. The specular reflection of Helium and Argon was demonstrated with very small diffuse scattering component. The combination of REMPI and molecular beam scattering apparatus is being developed. Less