Effects of vibrational frequency correlations on two-dimensional infrared spectra
Effects of vibrational frequency correlations on two-dimensional infrared spectra
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DOI：
10.1021/jp011768o
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发表时间：
2002-02-14
影响因子：
2.9
通讯作者：
Hochstrasser, RM
中科院分区：
文献类型：
--
作者：
Ge, NH;Zanni, MT;Hochstrasser, RM
描述了模拟和拟合二维红外光谱所需的响应函数，包括振动频率的分布、非谐性和振动器之间的耦合。引入了一种不涉及显式计算的简单方法来表征有助于 2D IR 的每个量子路径的谱线窄化特性。结果表明，需要在正频率象限和负频率象限中收集二维红外光谱，以便优化评估这些相关性所需的信息。描述了外差 2D IR（乙二醇中的丙酮和 D2O 中的乙酰脯氨酸-ND2）的两个实验示例，其中获得了脉冲延迟的常规回波序列和通常非重相信号的 2D IR 光谱。正如预测的那样，这两个例子的两组光谱都非常不同。仅当相关非均匀分布之间存在某种反相关时，后者才表现出回波。
The response functions needed for simulating and fitting two-dimensional infrared spectra are described including the distributions of vibrational frequency, anharmonicity, and coupling between vibrators. A simple method that does not involve explicit calculation is introduced to characterize the spectral line narrowing properties of each of the quantum paths contributing to 2D IR. It is shown that the 2D IR spectra need to be collected in both positive and negative frequency quadrants in order to optimize the information needed to evaluate these correlations. Two experimental examples of heterodyned 2D IR (acetone in ethylene glycol and acetylproline-ND2 in D2O) are described where the 2D IR spectra are obtained for both the conventional echo sequence of pulse delays and for the usually nonrephased signal. These two sets of spectra are quite different for both examples, as predicted. The latter exhibits an echo only when there is some anticorrelation between the relevant inhomogeneous distributions.