| Project/Area Number |
06554008
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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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 |
KINOSHITA Shuichi Osaka University, Department of Physics, Professor, 理学部, 教授 (10112004)
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| Co-Investigator(Kenkyū-buntansha) |
NIIKURA Shinji Spectra Physics Co., Manager, フィジックス社, 技術部長(研究員)
KANEMATSU Yasuo Osaka University, Department of Physics, Assitant Professor, 理学部, 助手 (00211855)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥15,600,000 (Direct Cost: ¥15,600,000)
Fiscal Year 1995: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1994: ¥9,600,000 (Direct Cost: ¥9,600,000)
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| Keywords | Stimulated light scattering / Phonons / Nonlinear optical effect / Laser spectroscopy / Ultrashort light pulse / フォノン生成 / フェムト秒レーザー / 光カー効果 |
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| Research Abstract |
In this study, we have developed ultrashort pulse lasers and have applied to phonon excitaion in condensed matter. For this purpose, we have constructed two Ti : sapphire laser systems ; a stable pulse laser with 100 fs duration and an ultrafast pulse laser with 10 fs duration. In the latter, we have employed a Ti : sapphire rod with 2 mm thickness instead of 2 cm, which is usually employed in commercially available lasers. By virtue of this thin rod, we can replace a prism pair having a high refractive index in the cavity with quartz prisms which show small third-order group velocity dispersion.
Using these laser systems, we have performed stimulated light scattering experiment to generate high-frequency coherent phonons. With inserting a prism pair to reduce the pulse width outside the cavity, we are able to investigate the phonon generations up to 300 cm^<-1> by means of stimulated light scattering for various disordered materials. Typical results are summarized as follows : (1) Benzene derivatives show a strong relaxational mode and broad low frequency phonon modes peaked at 60 cm^<-1>, which is in contrast to the result for alcohols. The alcohols show a weak relaxational mode and low frequency phonon modes peak at 30 cm^<-1>. (2) Various liquids are in principle categorized into the above two types. (3) Polymer is characterized by the lack of relaxational modes in the frequency range investigated and by the presence of low frequency modes peak at 80 cm^<-1>. Since the low frequency modes lie relatively high frequency region with moderate width, the time responses of polymers shows a nearly overdamped oscillation. It is concluded that the time-domain measurement is particularly useful to characterize the relationship between the relaxational mode and low frequency phonon modes.
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