| Project/Area Number |
04044154
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Kwansei Gakuin University |
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Principal Investigator |
KOYAMA Yasushi Faculty of Science, Kwansei Gakuin University, 理学部, 教授 (90079666)
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| Co-Investigator(Kenkyū-buntansha) |
COGDELL Rich グラスゴー大学, 植物学教室, 教授
COGDELL Richard J. Department of Botany, University of Glasgow
RICHARD J Co グラスゴー大学, 植物学教室, 教授
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1992: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Carotenoids / Photosynthesis / Light-harvesting complexes / Transient Raman / Electronic absorption / Fluorescence / Singlet energy levels / Solvent effects / 励起状態 / エネルギー伝達 / ラマン分光 / ケイ光分光 |
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| Research Abstract |
The 527 and 588nm pulses have been used, respectively, for pumping and probing (delay Ops) the S_1 and T_1 states of okenone which is bound to both the B830 LH2 complex and the chromatophores from Chromatium purpuratum BN5500. The results indicate that in the chromatophores there are at least two types of S_1 carotenoids with different lifetimes, i.e. one in the LH2 complex which is too short-lived to be detected and the other in either the reaction center or the LH2 complex which is long-lived. The results also indicate that at least two of the light-harvesting carotenoid molecules are in close connection in the LH2 com plex. [Ref. 1].
Fluorescence and fluorescence-excitation spectroscopy of the light-harvesting (LH2) complex of Rhodobacter sphareroides 2.4.1 has determined the energies of level I(2^1Ag^-), level II(^1Bu^-, level III(^1Bu^+) and level IV(3^1Ag^-) of the bound spheroidene. Internal conversion in spheroidene and spheroidene-to-bacteriochlo-rophyll energy transfer, as determined by fluorescence-excitation spectroscopy, suggest two different light-harvesting pathways, i.e. through level III(^1Bu^+) and through level I(2^1Ag^-). [Ref. 2].
The ^1Bu^+ energy of spheroidene exhibited a linear dependence on R(n)=(n^2-1)/(n^2 +2) in both nonpolar and polar solvents ; the line for polar solvents had a gentler slope and crossed the line for nonpolar solvents at R(n)=0.3. A theory was developed to explain the solvent effects. [Refs. 3 and 4]. The vibronically coupled C=C stretching frequencies in the ^1Ag^- and 2^1Ag^- states also showed similar dependence on R(n), which is explained in terms of vibronic coupling among the ^1Ag^-, 2^1Ag^- and 3^1Ag^- states. The environment of spheroidene in the LH2 and LH1 complexes was assessed on the basis of the above data.
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