Determination of the excited states of the electron centers and recording-readout processes in the X-ray storage material BaFBr
| Project/Area Number |
09450002
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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 |
Applied materials science/Crystal engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
KONDO Yasuhiro Graduate School of Engineering, Tohoku University Associate Professor, 大学院・工学研究科, 助教授 (20013534)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | X-ray Imaging / Imaging Plate / Photo-Stimulated Luminescence / Phosphors / Luminescence / Electron trap centers / 2-D detectors / Detectior of InfraRed Light / 二次元検出器 / 画像記録 / X線 / イオン結晶 / 色中心 / 発光分光 / 励起状態 / 赤外分光 / 光物性 |
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| Research Abstract |
In the storage phosphor of the X-ray image material, the X-ray photons generate electrons and holes which are trapped at vacancies and Eu^<++> impurities in the micro crystals ofBaFBr : Eu^<++>(storage process) and photoexcitation of the trapped electron induces the recombination of the electrons and holes at Eu impurity, emitting the uv-luminescence. This uv-luminescence is recorded and is used to construct the X-ray image (readout process). Although the storage-readout mechanism described above has been proposed in the early stage of the invention of the imaging plate, the storage-readout process is still controversial at present. To establish the clear model for the mechanism, I tried to measured thermal stability of the excited state of the trapped electrons and also to clarify the recombination path of the electrons and holes. For this measurements, a system for the infrared luminescence was constructed. Results are summerized as follows.
1) The temperature dependence of the luminescence intensity and its lifetime of the F center were measured and the thermal activation energy of the F centers in the excited state was obtained. This mechanism is identical to the that proposed by Takahashi.
2) The F(F^-)-center luminescence in the IP was measured for the first time and it is also shown that F(Br^-) center does not emit any IR luminescence. These results shows that the electron center can migrate in the micro crystals in the IP and that the fading of the stored image might be induced by the migration of holes which are thermally activated in shallowly trapped hole centers.
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Report
(3 results)
Research Products
(2 results)
