2003 Fiscal Year Final Research Report Summary
In-Situ Laser Detection for Aerosols and Toxic Chemicals associated with Aerosols
| Project/Area Number |
13358009
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAGASAKI Shinya The University of Tokyo, Graduate School of Frontier Sciences, Associate Professor, 大学院・新領域創成科学研究科, 助教授 (20240723)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Shuichi The University of Tokyo, Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (90262047)
YONEOKA Toshiaki The University of Tokyo, Graduate School of Engineering, Research Associate=, 大学院・工学系研究科, 助手 (40013221)
TANAKA Satoru The University of Tokyo, Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (10114547)
UETA Shinzo Mitsubishi Materials Co.Ltd., Director, 部長
KADO Shinichiro The University of Tokyo, High Temperature Plasma Center, Associate Professor, 高温プラズマ研究センター, 助教授 (10300732)
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| Project Period (FY) |
2001 – 2003
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| Keywords | aerosol / toxic chemicals / laser detection / in-situ detection / breakdown / multi-photone |
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| Research Abstract |
In this study, it was proved that laser breakdown causes through two main ionization mechanisms. One is multiphoton ionization, and the other is cascade ionization. From the breakdown of N_2 gas, it was founded that at low laser energy (<20mJ〜30mJ/pulse), cascade ionization effect was small, and multiphoton ionization effect was relatively large, and that at high laser energy(>20mJ〜30mJ/pulse), cascade ionization was main a mechanism. Introducing aerosols into N_2 gas led to promoting of cascade ionization of N_2 That is because of electrons produced on aerosols. Emission intensity from breakdown plasmas of Eu adsorbed on TiO_2 aerosols was founded to be larger than that of Eu existing freely from TiO_2. This is because of the size of aerosols. It is known that breakdown probability increases with the size of aerosols. On the other hand, the intensity of Ti I decreased as the amount of adsorbed Eu increased, meaning that TiO_2 was breakdowned by cascade ionization induced by electrons from adsorbed Eu.
Furthermore, the particles were completely dispersed in aqueous solutions and the realization of breakdown spectroscopic technique was validated by using the natural environmental waters. It was confirmed that the technique is useful for In-Situ quantitative detection of aerosols/dispersed particles in atmosphere and in environments and of toxic chemicals especially heavy metals associated with aerosols and particles.
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