1999 Fiscal Year Final Research Report Summary
Ortho-para conversion of hydrogen molecules at solid surfaces : elucidation of the mechanism and application to a new spin probe at surfaces
| Project/Area Number |
10440086
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
FUKUTANI Katsuyuki University of Tokyo, Institute of Industrial Science, Associate Professor, 生産技術研究所, 助教授 (10228900)
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| Co-Investigator(Kenkyū-buntansha) |
TSUNEYUKI Shinji University of Tokyo, Institute for Solid State Physics, Associate Professor, 物性研究所, 助教授 (90197749)
WIDE Markus University of Tokyo, Institute of Industrial Science, Research Associate, 生産技術研究所, 助手 (10301136)
OKANO Tatsuo University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (60011219)
MATSUMOTO Masuaki University of Tokyo, Institute of Industrial Science, Research Associate, 生産技術研究所, 助手 (40251459)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Hydrogen molecule / Solid surfaces / REMPI / Ortho-para conversion / Rotational state / Ortho-para separation |
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| Research Abstract |
Hydrogen molecules have internal degrees of freedom, nuclear spin and rotational motion, which are known to play an important role in the interaction with solid surfaces. The purpose of the present project is to elucidate the microscopic mechanism of the interaction difference between the ortho-and para-hydrogen with solid surfaces and the ortho-para conversion. In order to achieve this, we have developed a new experimental technique of rotational/spin-state selective thermal desorption spectroscopy by using resonance-enhanced multiphoton ionization, with which we have experimentally investigated the difference of the desorption energy between ortho- and para-hydrogen molecules and the ortho-para conversion rate at mesoporous alumina and copper surfaces. We have found the following results : 1. The desorption energy of hydrogen molecules at meso-pores of alumina is higher than that at particle surfaces, 2. The ortho-para conversion time is 32 min at meso-pores, 3. The ortho-para conversion time at particle surfaces is shorter than 7 min, 4. The desorption energy of the ortho-hydrogen is higher than that of para-hydrogen by about 6 meV. The ortho-para conversion is considered to be driven by the magnetic dipole interaction with impurity spins at surfaces. The difference of the desorption energy between ortho- and para-hydrogen is concluded to originate from the anisotropy of the adsorption potential at these surfaces.
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