System-Dependent Signatures of Electronic and Vibrational Coherences in Electronic Two-Dimensional Spectra

• Published in: The journal of physical chemistry letters 2012-06, Vol.3 (11), p.1497-1502
• Main Authors: Mančal, Tomáš, Christensson, Niklas, Lukeš, Vladimír, Milota, Franz, Bixner, Oliver, Kauffmann, Harald F, Hauer, Jürgen
• Format: Article
• Language: English
• Subjects: Spectroscopy, Photochemistry, and Excited States
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/jz300362k

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.