1995 Fiscal Year Final Research Report Summary
Dynamics of internal rotation related to the intramolecular charge-t transfer reactions
| Project/Area Number |
06453022
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical chemistry
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KAJIMOTO Okitsugu Graduate School of Science, Kyoto University Professor, 大学院・理学研究科, 教授 (30029483)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMURA Yo Graduate School of Science, Kyoto University Instructor, 大学院・理学研究科, 助手 (00222266)
YOSHIMURA Yosuke Graduate School of Science, Kyoto University Instructor, 大学院・理学研究科, 助手 (10192428)
HARA Kimihiko Graduate School of Science, Kyoto University Lecturer, 大学院・理学研究科, 講師 (80025436)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Internal rotation / Time-resolved fluorescence depletion / Intramolecular charge-transfer reactions / Solvation cluster / 9,9'-bianthryl / ビアントリル |
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| Research Abstract |
The aim of this project is to determine the internal rotation potentials of the compounds capable of forming an intramolecular charge-transfer (CT) state and then to observe the dynamics of the CT state formation on the twisting reaction coordinate. The following topics have been extensively studied
1. Determination of the potential energy surface of internal rotation
The potential energy surfaces for the internal rotation of 9,9'-bianthryl (BA) -rare gas and BA-Ar complexes were determined. In a He complex the small perturbation slightly splits the degenerate twisting levels whereas in Ar and O complexes the shape of the potential is drastically changed ; one well of the double well potential disappears.
2. The time-resolved fluorescence of BA complexes
The BA-Ar complex only emits the fluorescence from the excited S_1 state whereas the BA-H_2 O complex gives the fluorescence from both the S_1 and the CT states. The time profile of the BA-Ar fluorescence was found to be independent of the
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wavelength observed, which probably indicated the rapid IVR within the time resolution of the detecting system. On the other hand, the time profile of the BA-H_2O complex showed the wavelength dependence ; at the excitation wavelength 375 nm), it decayd very rapidly within 10 ps whereas at 380nm it increased first and then decreased with the time constant of 20 ps. The CT fluorescence increased with 20 ps rise time. This behavior indicates the presence of the intermediate state which probably be assignable to the vibarationally hot CT state
3. The observation of the relaxation processes with the time-resolved fluorescence depletion (TRFD) method
With the TRFD method, the rapid dephasing processes of the excited state of BA-Ar and BA-H_2O complexes have been observed. In the BA-Ar complexes, the observed dephasing of 10 ps corresponded to the intramolecular vibrational energy redistribution whereas in BA-H_2O complexes the observed 6 ps dephasing time could be attributed to both the IVR and CT state formation.
4. A simulation of the dynamic processes
The simultaneously occurring IVR and CT state formation in the BA-H2O complexes was simulated in terms of the time-evolution of the wavefunction prepared by the ps excitation. The observed behavior was well reproduced. Less
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Research Products
(12 results)
