1992 Fiscal Year Final Research Report Summary
FEMTOSECOND VIBRATIONAL RELAXATION OF EXCITED SINGLET STATES IN ORGANIC DYES USING A TEMPORAL INTENSITY CORRELATION TECHNIQUE OF STIMULATED FLUORESCENCES.
| Project/Area Number |
03804022
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理学一般
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| Research Institution | KAGAWA UNIVERSITY |
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Principal Investigator |
ITOH Hiroshi KAGAWA UNIVERSITY FACULTY OF EDUCATION ASSOCIATE PROFESSOR, 教育学部, 助教授 (60112249)
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| Co-Investigator(Kenkyū-buntansha) |
KAWASE Masaya KAGAWA UNIVERSITY FACULTY OF EDUCATION ASSOCIATE PROFESSOR, 教育学部, 助教授 (90224782)
NAKANISHI Shunsuke KAGAWA UNIV. FACULTY OF EDUCATION ASSOCIATE PROFESSOR, 教育学部, 助教授 (30155767)
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| Project Period (FY) |
1991 – 1992
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| Keywords | FEMTOSECOND RELAXATION / TEMPORAL CORRELATION / STIMULATED FLUORESCENCE / INCOHERENT LASER / ORGANIC DYE |
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| Research Abstract |
We have found striking signals which showed femtosecond modulation (quantum beat) or temporal peak shifts in correlation traces of stimulated fluorescences generated by exciting Cresyl Violet(CV) and Rhodamine 640 (Rh-640) or DODCI solution of high concentration at room temperature with broadband incoherent (bandwidth was 3- 7 nm) nanosecond dye laser. When the laser beam with a duration of 7 ns was divided into two beams with the wave vector k1 and k2, and one beam was variably delayed with respect to the other. The dye was irradiated with the k1 and k2 beams after focussed. Several wavelengths of lasers were employed to excite the dyes between 532 and 594 nm.
We consider that experimental results are due to the diffraction of the stimulated fluorescence from a dynamic grating initially formed by two exciting beams with femtosecond correlation time. The quantum beats are probably related to the femto-second vibrational dynamics in the excited state of the CV. on the other hand, it is thought that the peak shifts of Rh-640 and other dyes are caused by the depth of dynamic grating determined by balance between absorption of the pump beams and effective emission of the stimulated fluorescences from dye molecules. Moreover, the lack of the beats in the Rh-640 and the DODCI can be interpreted by the different displacement and energy gap between the ground- and excited-state potential surfaces for these dyes from those for the CV.
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