Šanda František, Perlík Václav, Lincoln Craig N, Hauer Jürgen
Faculty of Mathematics and Physics, Institute of Physics, Charles University , Ke Karlovu 5, Prague, 121 16 Czech Republic.
Photonics Institute, TU Wien , Gusshausstrasse 27, 1040 Vienna, Austria.
J Phys Chem A. 2015 Nov 5;119(44):10893-909. doi: 10.1021/acs.jpca.5b08909. Epub 2015 Oct 23.
Center line slope (CLS) analysis in 2D infrared spectroscopy has been extensively used to extract frequency-frequency correlation functions of vibrational transitions. We apply this concept to 2D electronic spectroscopy, where CLS is a measure of electronic gap fluctuations. The two domains, infrared and electronic, possess differences: In the infrared, the frequency fluctuations are classical, often slow and Gaussian. In contrast, electronic spectra are subject to fast spectral diffusion and affected by underdamped vibrational wavepackets in addition to Stokes shift. All these effects result in non-Gaussian peak profiles. Here, we extend CLS-analysis beyond Gaussian line shapes and test the developed methodology on a solvated molecule, zinc phthalocyanine. We find that CLS facilitates the interpretation of 2D electronic spectra by reducing their complexity to one dimension. In this way, CLS provides a highly sensitive measure of model parameters describing electronic-vibrational and electronic-solvent interaction.
二维红外光谱中的中心线斜率（CLS）分析已被广泛用于提取振动跃迁的频率-频率相关函数。我们将这一概念应用于二维电子光谱，其中CLS是电子能隙波动的一种度量。红外和电子这两个领域存在差异：在红外领域，频率波动是经典的，通常缓慢且呈高斯分布。相比之下，电子光谱会受到快速光谱扩散的影响，除了斯托克斯位移外，还会受到欠阻尼振动波包的影响。所有这些效应都会导致非高斯峰形。在这里，我们将CLS分析扩展到高斯线形之外，并在溶剂化分子锌酞菁上测试所开发的方法。我们发现，CLS通过将二维电子光谱的复杂性简化为一维，有助于对其进行解释。通过这种方式，CLS为描述电子-振动和电子-溶剂相互作用的模型参数提供了一种高度灵敏的度量。
