Line shape analysis of two-dimensional infrared spectra
Line shape analysis of two-dimensional infrared spectra
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DOI：
10.1063/1.4918350
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发表时间：
2015-06-07
影响因子：
4.4
通讯作者：
Cheatum, Christopher M.
中科院分区：
文献类型：
--
作者：
Guo, Qi;Pagano, Philip;Cheatum, Christopher M.
超快二维红外（2D IR）光谱探测飞秒到皮秒的时间尺度动力学，从溶剂化到蛋白质运动。频率-频率相关函数（FFCF）是光谱扩散的定量测量，其报告这些动态，并且在某些近似值内，可以直接从2D IR线形中提取。已经开发了多种方法来从2D IR光谱中提取FFCF，原则上，这些方法应该给出相同的FFCF参数，但是真实的实验系统的复杂性将不同地影响这些分析的结果。在这里，我们比较了五种常见的分析方法，使用模拟和实验的二维红外光谱，以了解切趾，非谐性，定相误差，和有限的信号-噪声比对这些分析的结果的影响。我们的研究结果表明，虽然所有的方法可以，在原则上，在理想化的情况下，产生的FFCF，在更现实的实验条件下，他们的行为完全不同，我们发现，中心线斜率分析产生的影响，我们测试之间的最佳妥协，是最强大的扭曲，他们造成的。(C)2015 AIP Publishing LLC.
Ultrafast two-dimensional infrared (2D IR) spectroscopy probes femtosecond to picosecond time scale dynamics ranging from solvation to protein motions. The frequency-frequency correlation function (FFCF) is the quantitative measure of the spectral diffusion that reports those dynamics and, within certain approximations, can be extracted directly from 2D IR line shapes. A variety of methods have been developed to extract the FFCF from 2D IR spectra, which, in principle, should give the same FFCF parameters, but the complexity of real experimental systems will affect the results of these analyses differently. Here, we compare five common analysis methods using both simulated and experimental 2D IR spectra to understand the effects of apodization, anharmonicity, phasing errors, and finite signal-to-noise ratios on the results of each of these analyses. Our results show that although all of the methods can, in principle, yield the FFCF under idealized circumstances, under more realistic experimental conditions they behave quite differently, and we find that the centerline slope analysis yields the best compromise between the effects we test and is most robust to the distortions that they cause. (C) 2015 AIP Publishing LLC.