Bonn 2025 – scientific programme

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MO: Fachverband Molekülphysik

MO 28: Ultrafast Dynamics IV

MO 28.5: Talk

Friday, March 14, 2025, 12:00–12:15, HS XVI

Time- and energy-resolved fluorescence measurements of collective effects in organic aggregates attached to rare gas clusters — •Aleksandr Demianenko, Moritz Michelbach, Sebastian Hartweg, and Frank Stienkemeier — Institute of Physics, University of Freiburg, Germany

Collective effects in organic semiconductors affect excited state lifetimes, important for organic optoelectronic and photovoltaic applications. A complete understanding of the energy level structure, and decay mechanisms require high spectral and temporal resolution. We present a setup combining conventional laser-induced fluorescence (LIF) spectroscopy with time-correlated single photon counting (TCSPC) and discuss advantages and implementation challenges. Using wavelength-tunable nanosecond dye laser pulses allows us to measure high-resolution LIF spectra of transitions to highly excited states of tetracene embedded in superfluid helium nanodroplets, or deposited on solid rare-gas clusters. The newly implemented TCSPC detection in combination with a femtosecond laser system is aimed at studying radiative and non-radiative decay mechanisms connected to collective effects in aggregates of polyacenes. This technique allows us to cover the sub-ns lifetime region not previously reachable in our fluorescence measurements.

Keywords: polyacenes; cluster isolation spectroscopy; rare-gas clusters; helium droplets; tcspc