System-Dependent Signatures of Electronic and Vibrational Coherences in Electronic Two-Dimensional Spectra.
In this work, we examine vibrational coherence in a molecular monomer, where time evolution of a nuclear wavepacket gives rise to oscillating diagonal- and off-diagonal peaks in two-dimensional electronic spectra. We find that the peaks oscillate out-of-phase, resulting in a cancellation in the corresponding pump-probe spectra. Our results confirm the unique disposition of two-dimensional electronic spectroscopy (2D-ES) for the study of coherences. The oscillation pattern is in excellent agreement with the diagrammatic analysis of the third-order nonlinear response. We show how 2D-ES can be used to distinguish between ground- and excited-state wavepackets. On the basis of our results, we discuss coherences in coupled molecular aggregates involving both electronic and nuclear degrees of freedom. We conclude that a general distinguishing criterion based on the experimental data alone cannot be devised.
†Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, Prague 121 16, Czech Republic.
Tomáš
T
Mančal
‡Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria.
Niklas
N
Christensson
§Department of Chemical Physics, Slovak Technical University, Radlinského 9, 81237 Bratislava, Slovakia.
Vladimír
V
Lukeš
‡Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria.
Franz
F
Milota
‡Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria.
Oliver
O
Bixner
‡Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria.|∥Faculty of Physics, Vienna University of Technology, Wiedner Hauptstrasse 8 - 10, 1040 Vienna, Austria.
Harald F
HF
Kauffmann
‡Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria.
Jürgen
J
Hauer
DFT-calculations; four-wave mixing; two-dimensional electronic spectroscopy; ultrafast dynamics; vibrational wavepackets