2000 Fiscal Year Final Research Report Summary
The electron-phonon interaction in liquid investigated by near-resonantly excited Ramen scattering spectra
| Project/Area Number |
11640315
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Osaka University |
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Principal Investigator |
WATANABE Junji Graduate School of Science, Osaka University Associate Professor, 理学研究科, 助教授 (60201191)
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| Co-Investigator(Kenkyū-buntansha) |
KINOSHITA Shuichi Graduate School of Science, Osaka University Professor, 理学研究科, 教授 (10112004)
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| Project Period (FY) |
1999 – 2000
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| Keywords | optical dephasing / secondary radiation / Raman scattering / electron-phonon interaction / β-carotene |
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| Research Abstract |
The ultrafast dynamics in disordered system has been extensively investigated by various optical measurements on dye molecules introduced into the system. It has been found that, in solutions at room temperature, the optical dephasing between the electronic ground and excited states occurs on the time scale of femtoseconds reflecting the dynamics of surrounding atoms and that the dephasing process cannot be described by a simple exponential decay. In this research, the optical dephasing of β-carotene in ethanol has been investigated by incoherent photon echo and the second-order optical processes. We found that the dephasing occured on the time scale of femtoseconds even at 50 K.These time-domain and frequency-domain measurements are analyzed by the dynamical model for the electron-phonon interaction. Since results of photon echo and second-order optical process are well reproduced by the model, we consider that the dynamical model with linear electron-phonon interaction is a good approximation for describing the ultrafast dephasing process in this system. In addition, the dephasing process of β-carotene molecule is approximately characterized by the slow modulation regime. From the viewpoint of adiabatic potential, the obtained value of E_<LR>/ω0=8 indicates that the electron-phonon interaction is relatively strong for the long conjugated system in β-carotene molecule. The dephasing in femtosecond time scale essentially comes from this relatively strong coupling
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