| Project/Area Number |
60540208
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Faculty of Engineering Science, Osaka University |
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Principal Investigator |
YOSHIMORI Akio Faculty of Engineering Science, Osaka University, 基礎工学部, 教授 (50013470)
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| Co-Investigator(Kenkyū-buntansha) |
MAKOSHI Kenji Faculty of Engineering Science, Osaka University, 基礎工学部, 助手 (10116098)
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| Project Period (FY) |
1985 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥400,000 (Direct Cost: ¥400,000)
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| Keywords | Tungsten (100) reconstructed surface / Computer simulation / Hydrogen adsorption / Condensation of adsorbed hydrogen / 昇温脱離 / 表面再構成 / W(100)表面 / 水素吸着 |
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| Research Abstract |
Surface reconstruction of W(100) and hydrogen adsorption effects, typical problems of ordering on metal surfaces, are investigated. Theoretical analyses on the experimental results particularly on thermal desorption spectra as well as symmetry properties are mode to confirm the phenomenological models. Two possible model Hamiltonians are considered for displacements of surface W atoms, and a lattice gas model is employed for adsorbed hydrogen atoms. One of two is eliminated by infrared absorption experiments of the adsorbed hydrogen vibration. Analyses of the model are made by computer simulation in canonical (fixed number of adsorbed hydrogen atoms) and grand canonical (variable number of adsorbed hydrogen atoms) ensembles. In the latter, two methods are used, one uses random sampling for the adsorbed hydrogen atoms and the other includes effective interactions for surface W atom displacements obtained after taking trace on the freedom of the lattice gas model of adsorbed hydrogen. Analyses are made, in particular, on the experimentally observed transition of the direction of the surface W atom displacement. The phase diagram is obtained by the canonical ensemble approach in qualitative agreement with the experimental one. Condensation of adsorbed hydrogen is suggested in the results, which is confirmed by the grand canonical approaches. The condensation does not occur in the W(100) surface, but it is indeed observed experimentally in the Mo(100) reconstructed surface with adsorbed hydrogen.
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