Ultrafast Intramolecular Relaxation and Wave‐Packet Motion in a Ruthenium‐Based Supramolecular Photocatalyst |
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| Authors: | Maria Wächtler Julien Guthmuller Stephan Kupfer Margherita Maiuri Daniele Brida Jürgen Popp Sven Rau Giulio Cerullo Benjamin Dietzek |
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| Affiliation: | 1. Leibniz‐Institute of Photonic Technology Jena (IPHT) e.V. Albert‐Einstein‐Str. 9, 07745, Jena (Germany), Fax: (+49)?3641‐206390;2. Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich‐Schiller University Jena, Helmholtzweg 4, 07743 Jena (Germany);3. Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12, 80233 (Poland);4. IFN‐CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano (Italy);5. Department of Physics and Center for Applied Photonics, University of Konstanz, 78457 Konstanz (Germany);6. Institute of Inorganic Chemistry I, University of Ulm, Albert‐Einstein‐Allee 11, 89081 Ulm (Germany);7. Humboldtstr. 10, 07743, Jena (Germany), and Center for Energy and Environmental Chemistry (CEEC) Jena, Philosophenweg 7a, 07743 Jena (Germany) |
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| Abstract: | The hydrogen‐evolving photocatalyst [(tbbpy)2Ru(tpphz)Pd(Cl)2]2+ (tbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, tpphz=tetrapyrido[3,2‐a:2′,3′‐c:3′′,2′′‐h:2′′′,3′′′‐j]phenazine) shows excitation‐wavelength‐dependent catalytic activity, which has been correlated to the localization of the initial excitation within the coordination sphere. In this contribution the excitation‐wavelength dependence of the early excited‐state relaxation and the occurrence of vibrational coherences are investigated by sub‐20 fs transient absorption spectroscopy and DFT/TDDFT calculations. The comparison with the mononuclear precursor [(tbbpy)2Ru(tpphz)]2+ highlights the influence of the catalytic center on these ultrafast processes. Only in the presence of the second metal center, does the excitation of a 1MLCT state localized on the central part of the tpphz bridge lead to coherent wave‐packet motion in the excited state. |
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| Keywords: | coherent vibrational motion DFT photophysics ruthenium time‐resolved spectroscopy |
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