Berlin 2014 – scientific programme
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MO: Fachverband Molekülphysik
MO 17: Excitons and Excitation Transfer (SYET 2)
MO 17.2: Talk
Thursday, March 20, 2014, 14:30–14:45, BEBEL HS213
Hopping transport of excited states in polymeric carbon nitride photocatalysts — •Christoph Merschjann1,2, Stefanie Tschierlei1, Stefan Lochbrunner1, Tobias Tyborski2,3, Arne Thomas4, and Thomas Schedel-Niedrig3 — 1Institut für Physik, Universität Rostock , D-18051 Rostock, Germany — 2Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany — 3Helmholtz-Zentrum Berlin, D-14109 Berlin, Germany — 4Technische Universität Berlin, D-10623 Berlin, Germany
The spectral and temporal development of optically excited states in polymeric carbon nitride (PCN) photocatalysts is investigated using time-resolved optical spectroscopy. By combining transient absorption results from a femtosecond pump-probe setup and transient photoluminescence using streak-camera and time-resolved single-photon counting investigations, the visible radiative emission upon UV excitation is obtained.
It is found that the decay of the emission exhibits a non-exponential behaviour over more than six decades in time (150 fs to 500 ns).
This characteristic points to a diffusive transport of localized excited states (Frenkel excitons). The underlying incoherent hopping transfer bears strong similarities to a small polaron transport. The consequences of such a comparably slow kind of transport for the catalytic activity of PCN are discussed.