title: Spectral lineshapes in nonlinear electronic spectroscopy.
abstract: We outline a computational approach for nonlinear electronic spectra, which accounts for the electronic energy fluctuations due to nuclear degrees of freedom and explicitly incorporates the fluctuations of higher excited states, induced by the dynamics in the photoactive state(s). This approach is based on mixed quantum-classical dynamics simulations. Tedious averaging over multiple trajectories is avoided by employing the linearly displaced Brownian harmonic oscillator to model the correlation functions. The present strategy couples accurate computations of the high-lying excited state manifold with dynamics simulations. The application is made to the two-dimensional electronic spectra of pyrene, a polycyclic aromatic hydrocarbon characterized by an ultrafast (few tens of femtoseconds) decay from the bright S2 state to the dark S1 state. The spectra for waiting times t2 = 0 and t2 = 1 ps demonstrate the ability of this approach to model electronic state fluctuations and realistic lineshapes. Comparison with experimental spectra [Krebs et al., New Journal of Physics, 2013, 15, 085016] shows excellent agreement and allows us to unambiguously assign the excited state absorption features.
authors.affiliation: Dipartimento di Chimica G. Ciamician, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy. artur.nenov@unibo.it marco.garavelli@unibo.it.
authors.forename: Artur
authors.initials: A
authors.lastname: Nenov
authors.affiliation: Dipartimento di Chimica G. Ciamician, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy. artur.nenov@unibo.it marco.garavelli@unibo.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Giussani
authors.affiliation: Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, Berlin, 12489, Germany.
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Fingerhut
authors.affiliation: Laboratoire de Chimie, Ecole Normale Suprieure de Lyon, 46, allée d'Italie, 69364 Lyon, France.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rivalta
authors.affiliation: Laboratoire de Chimie, Ecole Normale Suprieure de Lyon, 46, allée d'Italie, 69364 Lyon, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Dumont
authors.affiliation: Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
authors.forename: Shaul
authors.initials: S
authors.lastname: Mukamel
authors.affiliation: Dipartimento di Chimica G. Ciamician, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy. artur.nenov@unibo.it marco.garavelli@unibo.it and Laboratoire de Chimie, Ecole Normale Suprieure de Lyon, 46, allée d'Italie, 69364 Lyon, France.
authors.forename: Marco
authors.initials: M
authors.lastname: Garavelli