Stuttgart 2012 – scientific programme
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MO: Fachverband Molekülphysik
MO 2: Electronic Spectroscopy
MO 2.5: Talk
Monday, March 12, 2012, 11:30–11:45, V38.02
Spectroscopic Studies of the Electron Transfer in a Photocatalytic System based on an Ir(III)-Complex — •Alexandra Pazidis1, Aleksej Friedrich1, Antje Neubauer1, Felix Gärtner2, Henrik Junge2, Matthias Beller2, and Stefan Lochbrunner1 — 1Institut of physics, University of Rostock, Germany — 2Leibniz Institut for Catalysis Rostock, Germany
Iridium (III)-complexes have recently gained attention as photo-sensitizers in homogeneous water-reducing systems.
We investigate the excited state dynamics of [Ir(ppy)2(bpy)]+ (Ir-PS) in a photocatalytic system for hydrogen generation. In the primary reaction steps, the Ir(III)-complex is exited by light and relaxes to the lowest excited triplet state. Subsequently, it is reduced by triethylamine (TEA) as sacrificial reductant and transfers an electron to an iron-complex, which finally reduces the water to hydrogen.[1]
Emphasis is paid to monitor the processes on different time scales: The time range from fs to ns is investigated by transient absorption spectroscopy, luminescence measurements with a streak camera are done with ps to ms time resolution and real-time irradiation and absorption measurements are used to follow subsequent chemical reactions up to a duration of some minutes.
Rate constants for the quenching of the Ir-PS by TEA and by the iron-complex are determined and a interpretation of involved species is given.
References [1] F. Gärtner et al., Angew. Chem. 121, 10147 (2009).