Modelling Time-Resolved Two-Dimensional Electronic Spectroscopy of the Primary Photoisomerization Event in Rhodopsin

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• 作者：Ivan Rivalta ; Artur Nenov ; Oliver Weingart ; Giulio Cerullo ; Marco Garavelli ; Shaul Mukamel
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：July 17, 2014
• 年：2014
• 卷：118
• 期：28
• 页码：8396-8405
• 全文大小：395K
• ISSN：1520-5207

文摘

Time-resolved two-dimensional (2D) electronic spectra (ES) tracking the evolution of the excited state manifolds of the retinal chromophore have been simulated along the photoisomerization pathway in bovine rhodopsin, using a state-of-the-art hybrid QM/MM approach based on multiconfigurational methods. Simulations of broadband 2D spectra provide a useful picture of the overall detectable 2D signals from the near-infrared (NIR) to the near-ultraviolet (UV). Evolution of the stimulated emission (SE) and excited state absorption (ESA) 2D signals indicates that the S₁ 鈫?S_N (with N 鈮?2) ESAs feature a substantial blue-shift only after bond inversion and partial rotation along the cis 鈫?trans isomerization angle, while the SE rapidly red-shifts during the photoinduced skeletal relaxation of the polyene chain. Different combinations of pulse frequencies are proposed in order to follow the evolution of specific ESA signals. These include a two-color 2DVis/NIR setup especially suited for tracking the evolution of the S₁ 鈫?S₂ transitions that can be used to discriminate between different photochemical mechanisms of retinal photoisomerization as a function of the environment. The reported results are consistent with the available time-resolved pump鈥損robe experimental data, and may be used for the design of more elaborate transient 2D electronic spectroscopy techniques.