Weakly Robert B, Gaynor James D, Khalil Munira
Department of Chemistry, University of Washington, P.O. Box 351700, Seattle, Washington 98195, USA.
J Chem Phys. 2021 May 14;154(18):184202. doi: 10.1063/5.0047727.
Experimental demonstrations of polarization-selection two-dimensional Vibrational-Electronic (2D VE) and 2D Electronic-Vibrational (2D EV) spectroscopies aim to map the magnitudes and spatial orientations of coupled electronic and vibrational coordinates in complex systems. The realization of that goal depends on our ability to connect spectroscopic observables with molecular structural parameters. In this paper, we use a model Hamiltonian consisting of two anharmonically coupled vibrational modes in electronic ground and excited states with linear and bilinear vibronic coupling terms to simulate polarization-selective 2D EV and 2D VE spectra. We discuss the relationships between the linear vibronic coupling and two-dimensional Huang-Rhys parameters and between the bilinear vibronic coupling term and Duschinsky mixing. We develop a description of the vibronic transition dipoles and explore how the Hamiltonian parameters and non-Condon effects impact their amplitudes and orientations. Using simulated polarization-selective 2D EV and 2D VE spectra, we show how 2D peak positions, amplitudes, and anisotropy can be used to measure parameters of the vibronic Hamiltonian and non-Condon effects. This paper, along with the first in the series, provides the reader with a detailed description of reading, simulating, and analyzing multimode, polarization-selective 2D EV and 2D VE spectra with an emphasis on extracting vibronic coupling parameters from complex spectra.
极化选择二维振动 - 电子（2D VE）和二维电子 - 振动（2D EV）光谱的实验演示旨在绘制复杂系统中耦合电子和振动坐标的大小及空间取向。实现该目标取决于我们将光谱观测值与分子结构参数联系起来的能力。在本文中，我们使用一个模型哈密顿量，它由处于电子基态和激发态的两个非谐耦合振动模式组成，并带有线性和双线性电子 - 振动耦合项，以模拟极化选择二维EV和二维VE光谱。我们讨论了线性电子 - 振动耦合与二维黄 - 里斯参数之间以及双线性电子 - 振动耦合项与杜申斯基混合之间的关系。我们推导了电子 - 振动跃迁偶极矩的描述，并探讨了哈密顿量参数和非康登效应如何影响它们的幅度和取向。通过模拟极化选择二维EV和二维VE光谱，我们展示了二维峰位置、幅度和各向异性如何用于测量电子 - 振动哈密顿量的参数和非康登效应。本文与该系列的第一篇文章一起，为读者提供了对多模、极化选择二维EV和二维VE光谱进行读取、模拟和分析的详细描述，重点是从复杂光谱中提取电子 - 振动耦合参数。
