| Project/Area Number |
12135203
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
YAMAMOTO Shigehiko Institute of Applied Physics, University of Tsukuba, Professor, 物理工学系, 教授 (60251039)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Masahiro Institute of Applied Physics, University of Tsukuba, Associate Professor, 物理工学系, 助教授 (80282333)
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| Project Period (FY) |
2000 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥22,700,000 (Direct Cost: ¥22,700,000)
Fiscal Year 2003: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 2001: ¥12,100,000 (Direct Cost: ¥12,100,000)
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| Keywords | molecular beam / scanning tunneling microscopy / tunneling barrier / solid surface / electronic states / catalytic reaction / work function / activation barrier / 電気陰性度 / 解離吸着 / 超音速分子線 / STM / 走査型トンネル顕微鏡 / 反応活性化障壁 |
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| Research Abstract |
(a)Atomic-scale surface modification It was found that the collision of supersonic methane beams onto Pt (111) induces the generation of ethylidine, hydrocarbon and graphite, depending on the translational energy. It was also made clear that adsorption of such a small coverage of Cs as 0.006 ML increases the potential barrier for the reaction by about 200 meV, resulting in the termination of the reaction. These facts suggest the possibility of the control of surface reaction based on the translational energy of incident molecules.
(b)Work function observation in an atomic scale We have proposed a procedure to quantitatively discuss the work function in an atomic scale by means of a scanning tunneling microscope (STM). In conclusion, the adsorption of Cs atoms induces the electric dipole due to the difference in electronegativity as well as the non-local reduction in work function around the dipole. Furthermore, the microscopic observations of work function of transition metal nitrides prepared in Kyoto university by means of a non-contact atomic force microscope reveal the difference in microscopic features, depending on the preparation method.
(c)Combination of molecular beam apparatus and STM We have developed the combined system of molecular beam apparatus and STM. Also from helium atom scatterings, the non-local effect of the work function reduction due to adsorption was confirmed. Although the surface reaction of methane beams with a kinetic energy a little larger than the threshold energy is terminated after a small amount of adsorption of carbon related species, the incidence of the methane beam with a translational energy of 500meV completed monolayer graphite fully covering the surface. Further higher energy beams induces well-oriented monolayer graphite. The results demonstrate the possibility of precise control of adsorbates based on the kinetic energy.
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