1987 Fiscal Year Final Research Report Summary
THE STUDY OF THE EXCITED STATE AND ITS RELAXATION IN SOLIDS BY TIME-DELAYED DOUBLE EXCITATION IN PICOSECOND RANGE
| Project/Area Number |
60420011
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | YOHOKU UNIVERSITY |
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Principal Investigator |
HIRAI Masamitsu FACULTY OF ENGINEERING,TOHOKU UNIVERSITY PROFESSOR, 工学部, 教授 (90004275)
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| Co-Investigator(Kenkyū-buntansha) |
KAYANUMA Yousuke FACULTY OF SCIENCE,TOHOKU UNIVERSITY RESEARCH ASSISTANT, 理学部, 助手 (80124569)
SUZUKI Yoshiro FACULTY OF ENGINEERING,TOHOKU UNIVERSITY RESEARCH ASSISTANT, 工学部, 助手 (80133932)
KONDO Yasuhiro FACULTY OF ENGINEERING,TOHOKU UNIVERSITY ASSISTANT PROFESSOR, 工学部, 助教授 (20013534)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Time-Delayed Double Excitation System / Alkali Halide Crystals / Color Centers / Excitons / Chalcogenides / 超高速構造変化 |
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| Research Abstract |
1) Time-delayed excitation system with usign excimer and rudy lasers has been established.
2) By exciting NaCl, KBr and RbCl crystals with the excimer laser, the self trapped excitons (STE) at the lowest triplet state were created. At about 100<mu>s after the excitation with the excimer laser, the STE was re-excited to its higher excited state. The electronic relaxation in the STE and the conversion process from the STE to the F+H center pair were made clear. The relaxation mechanism in other materials are under investigation.
3) Optical absorption spectra of a-As_2S_3 were measured under the condition of light illumination and heating. It was concluded that light illumination and heating result in the tear-off of the bond between the layers constracting the film. In addition, we obtaied the fundamental process of the relaxation of the excited state in th is material.
4) The intensity and polarization of the hot luminescence of the F center in KCl and NaCl crystals have been investigated. No level crossing between 2s and 2p states of F center during relaxation was concluded.
5) In KI crystals above-100K, F+H centers were confirmed to be created by the thermal process from STE at the lowest triplet state. There are F+H center pairs created directly from higher excited states.
6) The level crossing in the strongly coupled electron-lattice ststem was theoretically investigated from a statistical view point on the resonant second emission. The hot luminescence in the F center was also investigated according to a classical model.
In conclusion, by establishing the time-delayed exciting system, the initial purpose to make clear the relaxation process of the excited state in the solids has been attained. The investigation will be extended to further wide range of materials.
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