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Theoretical Study on fluctuations in condensed phases and nonlinear spectroscopies

凝聚相涨落与非线性光谱的理论研究

基本信息

批准号：
13640506
负责人：
SAITO Shinji
金额：
$ 2.24万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In this study, we have investigated fluctuations in condensed phases ; multidimensional vibrational spectroscopy, phase transition dynamics of water, and chamical reactions in supercritical water.We have been theoretically investigating two-dimensinal (2D) Raman spectroscopy of liquids. As a two-dimensional NMR method, the multidimensional vibrational spectroscopies provide detailed information on dynamics that canot be obtained in conventional Raman spectroscopies. It was found that there exist changes in sign near the second time variable t_2 in the 2D Raman signals calculated with molecular dynamics simulation. The changes in sign are not seen in the signals based on normal mode descriptions. Thus it was found that they are related to anharmonic dynamics of the system. Various analyses have been made to understand what kind of dynamics is seen in the 2D Raman signals of liquid CS_2. We have found that a rotation-rotation dynamical coupling is the dominant contribution of the 2D Raman signal of liquid CS_2. The temperature dependence of the 2D Raman signal has been analyzing.We have analyzed the melting process of ice by using molecular dynamics simulations. It was found that the melting is followed by disorders of hydrogen bond network in the ice. We have analyzed the dynamics of translational and rotational motions and density fluctuation in the melting process.The dissociation of formic acid in a sub- and super-critical water has been also investigated.

本论文主要研究了凝聚相的涨落、多维振动光谱、水的相变动力学和超临界水中的查米卡尔化学反应，并从理论上研究了液体的二维拉曼光谱。作为一种二维NMR方法，多维振动光谱提供了常规拉曼光谱无法获得的详细动力学信息。发现分子动力学模拟计算的二维拉曼信号在第二时间变量t2附近存在符号变化。在基于正常模式描述的信号中看不到符号的变化。因此，它被发现，它们是有关的非谐动力学系统。为了理解在液态CS_2的二维拉曼信号中所看到的是什么样的动力学，已经进行了各种分析。发现液态CS_2的二维拉曼信号的主要贡献是转动-转动动力学耦合。分析了二维拉曼信号的温度依赖性，并利用分子动力学方法模拟了冰的融化过程。结果表明，冰的融化伴随着冰中氢键网络的紊乱。我们分析了熔化过程中的平移、旋转运动和密度涨落动力学，并研究了甲酸在亚、超临界水中的离解。