| Project/Area Number |
07455341
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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 |
工業物理化学
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| Research Institution | Osaka University |
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Principal Investigator |
MAJIMA Tetsuro Osaka University, The Institute of Scientific and Industrial Research, Associate Professor, 産業科学研究所, 助教授 (00165698)
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| Co-Investigator(Kenkyū-buntansha) |
SAJI Sachiko Osaka University, The Institute of Scientific and Industrial Research, Research, 産業科学研究所, 助手 (50197844)
ISHIDA Akito Osaka University, The Institute of Scientific and Industrial Research, Research, 産業科学研究所, 助手 (20184525)
高椋 節夫 大阪大学, 産業科学研究所, 教授 (50029849)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥7,900,000 (Direct Cost: ¥7,900,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥7,200,000 (Direct Cost: ¥7,200,000)
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| Keywords | Radiation chemistry / Photochemistry / Radical ions |
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| Research Abstract |
Photophysical and chemical properties of radical ions of aromatic compounds in the excited states have been clarified by a pulse radiolysis-laser flash photolysis combined method. The lifetimes of radical cations and anions of cis- and trans-stibene (c-St and t-St) and radical anions of dicyanoanthracene, phenazine, and anthraquinones in the excited states were measured for the first time and their transient phenomena such as the photoelectron ejection, c-t isomerization, and selective hole and electron transfer quenching of the radical cations and anions in the excited states, respectively, were investigated. In the deactivation of radical cations of c-St in the excited doublet state (c-St^<*+**>), the internal conversion competes with the isomerization to t-St^<*+> in a quantum yield of 0.49, whereas t-St^<*+**> is only deactivated via internal conversion. Lifetimes of t-St^<*+**> and c-St^<*+**> are estimated to be approximately 240 and 120 ps, respectively. The shorter lifetime of
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c-St^<*+**> is attributed to isomerization and conversion to another product via twisting about the central C=C double bond. St radical anions in the excited doublet state (St^<*-**>) undergo unimolecular isomerization from c-St^<*-> to t-St^<*->, photoelectron ejection, and electron transfer to biphenyl added as a quencher. From the selective electron transfer from St^<*-**> to biphenyl (Bp), the lifetimes of c-St^<*-**> and t-St^<*-**> are estimated to be approximately 1.5 and 2.5 ns, respectively. The shorter tau of c-St^<*-**> is attributed to isomerization via twisting about the central C=C double bond. The tau values of c-St^<*-**> and t-St^<*-**> are 1 order of magnitude longer than those of c-St^<*+**> and t-St^<*+**>. Lifetimes of approximately 4 ns are estimated for M^<*-**> (M=dicyanoanthracene, phenazine, and anthraquinones). The shorter lifetimes of 1.0-1.4 ns for methyl and chloro substituents on anthraquinone are explained in terms of internal conversion accelerated by rotatio of the substituents. The energy gap between the excited and ground states of M^<・-> is a singnficant factor for the rate of the internal conversion. A solvated pair of M and quencher^<・-> is suggested as an intermediate in the electron-transfer quenching of M^<*-**> by quencher such as fumaronitile. Less
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