Molecular dynamics simulation study of N-methylacetamide in water.: II.: Two-dimensional infrared pump-probe spectra
Molecular dynamics simulation study of N-methylacetamide in water.: II.: Two-dimensional infrared pump-probe spectra
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DOI：
10.1063/1.1580808
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发表时间：
2003-07-22
影响因子：
4.4
通讯作者：
Cho, MH
中科院分区：
文献类型：
--
作者：
Kwac, K;Cho, MH
考虑系统-浴槽相互作用，对三能级系统的二维红外泵浦-探测光谱进行了理论描述。利用从头计算和分子动力学模拟得到的N-甲基乙酰胺分子在D2 O中酰胺I模振动频率的关联函数，计算了时间分辨二维泵浦-探测光谱随泵浦-探测脉冲延迟时间的变化，并与实验结果进行了比较.我们发现振动退相在2 ps时间尺度上变得均匀，这比实验结果快一些。理论分析表明，二维轮廓的倾斜程度与酰胺I模频率波动的相关函数成线性关系。因此，它建议，二维红外泵浦探测光谱可以提供一个直接的信息上的振动频率波动动力学和静态不均匀性的大小。(C)2003年，美国物理学会。
A theoretical description of two-dimensional (2D) IR pump-probe spectroscopy of a three-level system is presented by taking into account the system-bath interaction. By using the correlation function of the fluctuating amide I mode frequency of N-methylacetamide in D2O, which was obtained by carrying out both ab initio calculations and MD simulations, the time-resolved 2D pump-probe spectra as a function of pump-probe pulse delay time are calculated and compared with experiment. We found that the vibrational dephasing becomes homogeneous on the 2 ps time scale, which is a bit faster than the experimental result. It is theoretically shown that the degree of slant of 2D contours is linearly proportional to the correlation function of the fluctuating amide I mode frequency. Consequently, it is suggested that the 2D IR pump-probe spectroscopy can provide a direct information on the vibrational frequency fluctuation dynamics and on the magnitude of static inhomogeneity. (C) 2003 American Institute of Physics.