2009 Fiscal Year Final Research Report
Multiphoton reduction of lanthanide ions and isotope enrichment by a high intensity laser
| Project/Area Number |
19350016
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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 |
Physical chemistry
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| Research Institution | Osaka City University |
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Principal Investigator |
NAKASHIMA Nobuaki Osaka City University, 大学院・理学研究科, 教授 (00106163)
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| Co-Investigator(Kenkyū-buntansha) |
YATSUHASHI Tomoyuki 大阪市立大学, 大学院・理学研究科, 准教授 (70305613)
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| Project Period (FY) |
2007 – 2009
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| Keywords | 多光子反応 / 同位体分離 / 反応制御 |
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| Research Abstract |
Eu^<3+>→Eu^<2+> Reduction
Europium 3+ ions in methanol were found to be reduced to the corresponding 2+ ions upon irradiation with intense femtosecond laser pulses. The excitation wavelength of 800 nm was nonresonant with their electronic transitions of Eu^<3+>. It is notable that femtosecond white-light laser was generated when the reactions occurred. The mechanisms can be explained in terms of solvated electron formation followed by the reduction. The electron ejection in a focused beam in solution has been known to be accompanied by white-light laser.
Sm^<3+>→Sm^<2+> Reduction
Samarium 3+ ions in methanol were found to be reduced to the corresponding 2+ ions upon irradiation with intense femtosecond laser pulses. The reduction was observed at both pulses with central wavelengths of 403 nm converted from an 800-fs fundamental pulse and 800 nm with a duration of 43 fs. When the laser wavelength was tuned to the 4f-4f absorption at 403 nm corresponding to the ^6P_<3/2>←^6H_<5/2> transitio
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n, the the reduction occurred by multiphoton absorption presumably due to reaching the deep charge transfer state. In the case of excitation by 800-nm pulses of the fundamental wavelength of the Ti:sapphire laser, the reduction is considered to occur via solvent ionization followed by electron capture by Sm^<3+>. The product Sm^<2+> was detected by its fluorescence, which was observed for the first time in solution and showed a broad spectrum peak around 750 nm with a quantum yield of 0.050 in methanol in the presence of 15C5-ether.
Isotope Enrichment
The molar extinction coefficient of the ^6P_<3/2>←^6H_<5/2> transition is reportedly 10% different between ^<144>Sm^<3+> and ^<154>Sm^<3+> in solution : therefore, different isotope distributions among Samarium 2+ ions should be realized after the multiphoton reduction from Sm^<3+> to Sm^<2+>. This confirmation is currently in progress.
Preliminary results for Yb^<3+>→Yb^<2+> Reaction
Yb^<3+> has successfully reduced to Yb^<2+> by femtosecond pulse excitation with pulse duration of about 100 fs at three wavelengths of 800 nm, 970 nm, and 1930 nm. Yb^<3+> has the 4f-4f transition at 970 nm ; however, resonance enhancement for the formation of Yb^<2+> was not clear at this stage. Less
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