Effects of intermolecular vibrational coupling and liquid dynamics on the polarized Raman and two-dimensional infrared spectral profiles of liquid N,N-dimethylformamide analyzed with a time-domain computational method
Effects of intermolecular vibrational coupling and liquid dynamics on the polarized Raman and two-dimensional infrared spectral profiles of liquid N,N-dimethylformamide analyzed with a time-domain computational method
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DOI：
10.1021/jp060014c
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发表时间：
2006-04-13
影响因子：
2.9
通讯作者：
Torii, H
中科院分区：
文献类型：
--
作者：
Torii, H
一个时域方法计算偏振拉曼和二维红外（2D-IR）光谱，包括对角频率调制（在系统中的单个分子）和非对角（分子间）振动耦合的影响，并适用于液体N，N-二甲基甲酰胺的酰胺I带的情况。结果表明，共振非对角振动耦合和由此产生的振动模式的离域的效果是清楚地看到的偏振Rarnan光谱和一些光谱特征（特别是作为不对称的强度图案）的非重合效应在2D-IR光谱。讨论了最适合于观察这种效应的二维红外光谱（关于偏振条件）的类型。在偏振拉曼光谱的观测值与计算值相一致的基础上，还计算了瞬态红外吸收各向异性的时间依赖性。讨论了与这些光信号的时域和频域特征相关的振动模离域程度的评价方法。的性质的分子运动（关于液体动力学）是有效的对角频率调制也检查。
A time-domain method for calculating polarized Raman and two-dimensional infrared (2D-IR) spectra that includes the effects of both the diagonal frequency modulations (of individual molecules in the system) and the off-diagonal (intermolecular) vibrational coupling is presented and applied to the case of the amide I band of liquid N,N-dimethylforimamide. It is shown that the effect of the resonant off-diagonal vibrational coupling and the resulting delocalization of vibrational modes is clearly seen as the noncoincidence effect in the polarized Rarnan spectrum and some spectral features (especially as asymmetric intensity patterns) in the 2D-IR spectra. The type of 2D-IR spectra (concerning the polarization condition) most appropriate for observing this effect is discussed. On the basis of the agreement between the observed and calculated band profiles of the polarized Raman spectrum, the time dependence of the transient IR absorption anisotropy is also calculated. The method of evaluating the extent of delocalization of vibrational modes that is relevant to the features of these optical signals in the time and frequency domains is discussed. The nature of the molecular motions (concerning the liquid dynamics) that are effective on the diagonal frequency modulations is also examined.