Hannover 2020 – scientific programme

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MO: Fachverband Molekülphysik

MO 4: Electronic Spectroscopy I

MO 4.4: Talk

Monday, March 9, 2020, 15:00–15:15, f142

Time- and frequency-resolved TOF-MS and photoion imaging on tetracene multimers — •Marco Flock and Ingo Fischer — University of Wuerzburg, Institute of Physical Chemistry

Singlet fission (SF) describes the spin-allowed splitting of a photoexcited singlet state into two triplet states localized at two chromophores in a molecular system. To enable SF, the triplet energy of the chromophore must be half or lower than its singlet energy. This condition is fulfilled by tetracene making it a promising model system for the investigation of the SF process. The photophysical properties of the tetracene dimer and trimer were investigated by time- and frequency-resolved time of flight (TOF) photoionization and photoion imaging experiments in a molecular beam. The latter ones allow the exclusion of signals originating from fragmentation of higher order clusters. Frequency-resolved measurements revealed an ongoing red-shift of the dimer and trimer absorption compared to the monomeric species. Time-resolved measurements offered a completely different behavior for all three species: While monomeric tetracene shows no activity on the ps timescale, the dimer signal decays monoexponentially on the order of 100 ps and the trimer species shows a two-step relaxation with time constants of around 50 ps and 1 ns. The observed dynamics can be attributed to photophysical processes after photoexcitation and thus might play a role in the SF process of tetracene multimers.