2001 Fiscal Year Final Research Report Summary
Optical second harmonic spectroscopy of the surface and interface electronic states
| Project/Area Number |
10440090
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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 | Japan Advanced Institute of Science and Technology |
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Principal Investigator |
MIZUTANI Goro School of Materials Science, Japan Advanced Institute of Science and Technology, Associate Professor, 材料科学研究科, 助教授 (30183958)
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| Project Period (FY) |
1998 – 2001
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| Keywords | Surface optical second harmonic spectroscopy / Raman spectroscopy / Photocatalyst / Titanium dioxide / Ziegler-Natta catalyst / Au / Surface electronic resonance / Ge |
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| Research Abstract |
The objective of this research project is to explore the surface and interface electronic levels within several electron volts of Fermi level and relate them to the driving forces of typical surface and interface phenomena. The target material systems are (1) catalyst, (2) nanostructured metals, and (3) semiconductor structures.
(1) I have clarified that the surface band gap of photocatalyst TiO_2 has a larger gap energy than that of the bulk for (110) face. I have also found that the wavefunction of the electronic states of this surface varies drastically as a function of the energy. I have also found that the band gap shifts to the higher energy side when the material is catalytically activated by UV light. I have found a correlation between the catalytic activity of the Ziegler-Natta catalyst and the emergence of an edge vibrational mode of α-TiCl_3 granules at 224cm^<-1>.
(2) I have found a resonance in SH intensity from Au films on glass or NaCl(100). Besides plasmon resonance, I have found resonances of the transitions between electronic levels of Au(111) and (100) surfaces. I succeeded in following the variation of the electronic states of this metal as its film grows.
(3) I have found a new electronic resonance of Ge(111)/thermal oxide interface near 【planck's constant】ω=1.17eV. This resonance was not found for a native oxide interface. The SH intensity patterns as a function of the azimuthal angle are quite different between the thermal oxide and native oxide interface. This result suggests that the electronic states of the Ge interface is sensitive to the oxidation condition and offers a basic information for the semiconductor material physics using Ge and Si.
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