Excitation states and defect formation in high purity silica glass under gamma-ray or excimer-laser irradiation
| Project/Area Number |
03452156
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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 |
電子材料工学
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| Research Institution | Waseda University |
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Principal Investigator |
OHKI Yoshimichi Department of Electrical Engineering, Waseda University, Professor, 理工学部, 教授 (70103611)
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| Co-Investigator(Kenkyū-buntansha) |
NAGASAWA Kaya Department of Electrical Engineering, Shonan Institute of Technology, Associate, 工学部, 助教授 (20180474)
SOHTA Takayuki Department of Electrical Engineering, Waseda University, Associate Professor, 理工学部, 助教授 (90171371)
HAMA Yoshimasa Science and Engineering Research Laboratory, Waseda University, Professor, 理工学研究所, 教授 (40063680)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1992: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1991: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Keywords | silica glass / excimer laser / two-photon absorption process / point defects / synchrotron radiation / radiation / defect formation / エキシマレ-ザ |
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| Research Abstract |
The purpose of this study is to clarify the structural and optical properties of point defects in a-SiO_2, and their formation mechanisms under ionizing radiations or laser photons. The emphasis is placed on (i) the characterization of preexisting diamagnetic defects and radiation-induced paramagnetic defects, and (ii) the establishment of the link between the diamagnetic defects and radiation-induced paramagnetic defects. The outline of the present study is as follows.
1.Defects and optical absorption bands associated with excess oxygen are identified. Two forms of excess oxygen are identified: peroxy linkage and interstitial oxygen. An optical absorption band at 3.8 eV is associated with peroxy linkages.
2.Characterization of new paramagnetic defects induced by 7.9-eV photons is performed. With the help of computer simulation analyses of the ESR spectra, the paramagnetic defects are identified to be ClO_x radicals (x=2,3).
3.Time-resolved photoluminescence (PL) measurements are carried out on a series of silicas under 7.9-eV pulsed laser excitation. Correlations of several PL bands with point defects are studied.
4.Paramagnetic defects induced by 6.4-eV excimer laser are studied on a series of silicas. Effects of the oxygen stoichiometry and hydroxyl content on the defect species and their concentrations are observed. It is shown that precursor transformation dominates in laser-induced defect formation.
5.Photon-energy dependence of the creation of paramagnetic defects is investigated by means of ESR and uv-vuv optical absorption measurements, using 6.4-eV and 7.9-eV photons, and gamma rays as irradiation sources. Correlations between the preexisting diamagnetic defects and laser-induced paramagnetic defects are investigated.
6.The effect of hydrogen on the photogeneration of E' centers is studied by means of ESR and uv-vuv absorption measurements. It is found that the creation of E' centers from neutral oxygen vacancies is enhanced in the presence of hydrogen.
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Report
(3 results)
Research Products
(10 results)
