SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster Session I

CPP 17.8: Poster

Monday, March 27, 2023, 18:00–20:00, P3

Unraveling Structural Dynamics in Excimer Formation Using Ultrafast Electron Diffraction — •Sebastian Hammer¹, Laurenz Kremeyer¹, Tristan Britt¹, Maximilian Rödel², Syed Ali Hassan¹, Jens Pflaum^2,3, and Bradley Siwick¹ — ¹Departments for Physics and Chemistry, McGill University, Montreal, QC H3A 2K6, Canada — ²Experimental Physics VI, University of Würzburg, 97074 Würzburg — ³Bayerisches Zentrum für Angewandte Energieforschung (ZAE Bayern), 97074 Würzburg

Excimer formation, i.e. the formation of an excited dimer state which is accompanied by structural deformations in the local inter-molecular geometry, is a common phenomena in molecular solids and crucially determines the opto-electronic properties of the material. While the process is understood well on a theoretical level [1], direct observational evidence of the underlying structural dynamics are experimentally challenging.

In recent years, the technique of ultrafast electron diffraction (UED) has proven to be capable of unraveling the structural dynamics of molecular single crystals after photo-excitation [2]. Using the prototypical excimer system zinc-phthalocyanine in its crystallographic α-phase [3], we show that UED experiments on polycrystalline thins-films can disclose the structural dynamics accompanying excimer formation. We gratefully acknowledge funding from the DFG (Project 490894053).

[1] Bialas et al. J. Chem. Phys. C. 126 4067-4081 (2022)

[2] Gao et al. Nature. 496 343-346 (2013)

[3] Hammer et al., Mater. Horiz.. (2022)