| Project/Area Number |
63460024
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 | Tohoku University |
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Principal Investigator |
TAKAHASHI Takashi Tohoku University, Department of Physics, Research Associate, 理学部, 助手 (00142919)
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| Co-Investigator(Kenkyū-buntansha) |
KONO Shozo Tohoku University, Research Institute for Scientific Measurements, Professor, 科学計測研究所, 教授 (60133930)
SUZUKI Shoji Tohoku University, Department of Physics, Assistant Profesor, 理学部, 助教授 (10091703)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥5,800,000 (Direct Cost: ¥5,800,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Inverse Photoemission / Photoemission / Electronic State / Unoccupied State / Superconductor / Grating / 斜入射分光器 / 高温超伝導体 / 角度分解 / 非占有電子状態 / 斜入射型分光器 / プエルミ液体状態 |
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| Research Abstract |
1. A new electron gun with high-current density for use of inverse photoemission measurement has been designed. The electron gun has a BaO dispenser cathode as an electron emitter and a four electron-lense system to collimate the electron beam. It can be operated under ultrahigh vacuum (10^<-10>Torr) and gives 1 to 2 muA at the energy of 10 - 20 eV.
2. Two types of novel superconductors were studied with the newly designed electron gun at the constant-photon-energy mode.
(1) Angle-integrated and angle-resolved inverse photoemission spectra of cuprate high-Tc superconductors were measured. The experimental results show that doping of carriers produces new electronic states in the charge-transfer gap in the insulator instead of shifting the Fermi level. It was also found that the gap states consist of two dispersive bands crossing the Fermi level.
(2) An inverse photoemission measurement on K^^3C^^<60> shows that doping of alkali-metals into C^^<60> cause a non-rigid filling of the LUMO band, leaving a pseudo-gap at the Fermi level.
3. A new XUV spectrometer with high efficiency has been designed. The spectrometer is basically a non-Roland type grazing incidence spectrometer, designed for energy-range of 20 - 100 eV. An incident light at first collected with a large toroidal mirror then enters a 1/1200 grating for dispersing. The spectrometer has been tested with the He I resonance line as a reference and was found to give a satisfactory capability for dispersing-type inverse photoemission measurement.
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