title: Modelling time-resolved two-dimensional electronic spectroscopy of the primary photoisomerization event in rhodopsin.
abstract: 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 → SN (with N ≥ 2) ESAs feature a substantial blue-shift only after bond inversion and partial rotation along the cis → 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 → 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-probe experimental data, and may be used for the design of more elaborate transient 2D electronic spectroscopy techniques.
authors.affiliation: Université de Lyon , CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rivalta
authors.forename: Artur
authors.initials: A
authors.lastname: Nenov
authors.forename: Oliver
authors.initials: O
authors.lastname: Weingart
authors.forename: Giulio
authors.initials: G
authors.lastname: Cerullo
authors.forename: Marco
authors.initials: M
authors.lastname: Garavelli
authors.forename: Shaul
authors.initials: S
authors.lastname: Mukamel
mesh_terms: D007536:Isomerism; D008962:Models, Theoretical; D055668:Photochemical Processes; D011789:Quantum Theory; D012243:Rhodopsin / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D012243:Rhodopsin