Bonn 2025 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 5: Ultrafast Dynamics I

MO 5.6: Vortrag

Dienstag, 11. März 2025, 12:15–12:30, HS XVI

Excited state dynamics of 4a,4b-Azaboraphenanthene — •Jonas Fackelmayer, Michael Bühler, Michael Müller, Jannik Markert, and Ingo Fischer — Julius-Maximilians Universität, Würzburg, Deutschland

With growing interest in renewable energy generation, efficiently harnessing solar power has emerged as a major focus of both research and industry. The efficiency of organic solar cells might be increased significantly utilizing the photophysical process of singlet fission, a process in which a single excited singlet state splits into two triplet states therefore increasing the number of charge carriers generated from a single photon. Among the molecules that exhibit this process, polycyclic aromatic hydrocarbons (PAHs) are particularly noteworthy, as their optoelectronic properties can be tailored through the substitution of carbon units with boron and nitrogen.

In our most recent study we investigated the excited states dynamics of 4a,4b-azaboraphenanthene by picosecond time-resolved photoionization in a supersonic jet. A resonance-enhanced multi photon ionization (REMPI) spectrum reveals the S₁ origin at around 22880 cm⁻¹ and shows many vibronic bands. Time-resolved time-of-flight and photoelectron imaging experiments with pump wavelengths between 401 and 437 nm and probe wavelengths of 351 and 263,5 nm yield time constants between 20 and 35 ps. The experiments are accompanied by computational studies to gain further insights into the involved vibrational modes and deactivation mechanisms.

Keywords: time-resolved spectroscopy; velocity map imaging; photoeletron spectroscopy; excited state dynamics