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Solvent-Solute Interaction in Liquid and Solid Phases of Ethanol Probed by Photon Echo Spectroscopy

用光子回波光谱法探测乙醇液相和固相中的溶剂-溶质相互作用

基本信息

批准号：
08640405
负责人：
WATANABE Junji
金额：
$ 1.41万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640405/
关键词：
Photon Echo Optical Dephasing Solvent-Solute Interaction Beta-Carotene Non-Markovian Phonon Density of States

项目摘要

The optical dephasing of dye molecules in solution has been extensively investigated by various experimental methods and it is shown that the dephasing occurs on the time scale of femtoseconds with a non-Markovian nature. Since photon echo spectroscopy is a powerful tool for investigating solvation dynamics, several groups report echo responses measured at room temperature utilizing femtoseconds laser pulses. However reports on the temperature dependence of solvation dynamics are quite limited. The investigation of temperature dependence is important because it gives detailed information about the solvation dynamics.In this research, the solvation dynamics of beta-carotene molecules in ethanol has been investigated by incoherent photon echo spectroscopy at various temperatures from 300 K to 50 K.Experimental results are analyzed based on a dynamical model for a dephasing in femtoseconds and a stochastic model for a slow energy fluctuation. Using parameter values for the dynamical model determined from fluorescence spectra, we obtain amplitude and correlation time of the slow energy fluctuation in picoseconds time scale in solid phase of ethanol. It is shown that the fast response of echo signals in femtoseconds time scale essentially comes from the relatively strong electron-phonon coupling in this system and that the slow energy fluctuation decreases the rephasing process resulting in much faster response. The incoherent photon echo probes the slow energy fluctuation in picosecond order, Which is longer than the delay time between two excitation pulses.

通过各种实验方法对溶液中染料分子的光学脱相进行了广泛的研究，结果表明，染料分子的光学脱相发生在飞秒的时间尺度上，具有非马尔可夫性质。由于光子回波光谱是研究溶剂化动力学的有力工具，几个小组报告了利用飞秒激光脉冲在室温下测量的回波响应。然而，关于溶剂化动力学的温度依赖性的报道相当有限。温度依赖性的研究是重要的，因为它提供了有关溶剂化动力学的详细信息。在本研究中，利用非相干光子回波光谱研究了β -胡萝卜素分子在300 ~ 50 K不同温度下在乙醇中的溶剂化动力学。基于飞秒减相的动力学模型和慢能量波动的随机模型对实验结果进行了分析。利用荧光光谱确定的动力学模型参数值，得到了乙醇固相中皮秒级慢能量波动的幅值和相关时间。结果表明，飞秒时间尺度回波信号的快速响应本质上来自于系统中较强的电子-声子耦合，缓慢的能量波动减少了重相位过程，从而使响应速度大大提高。非相干光子回波探测的是皮秒级的慢能量波动，比两个激发脉冲之间的延迟时间要长。