Mainz 2026 – scientific programme

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MO: Fachverband Molekülphysik

MO 4a: Ultrafast Structural Dynamics II

MO 4a.3: Talk

Monday, March 2, 2026, 17:30–17:45, P 110

Imaging Coupled Electronic-Nuclear Dynamics in Dimethyl-Substituted Furan — •Athira Mini Santhosh¹, Jin Cheng², Simona Djumayska³, Sudhir Kumar¹, Joanne Woodhouse¹, Simone Stahl¹, Hui Jiang², Tianyu Wang², Daniel Keefer³, Dao Xiang², and Kasra Amini¹ — ¹Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin, Germany — ²Shanghai Jiao Tong University, 200240 Shanghai, China — ³Max-Planck-Institut für Polymerforschung, 55128 Mainz, Germany

Excited-state relaxation in 2,5-dimethylfuran (DMF) involves competing ring-opening and ring-puckering pathways near conical intersections. Time-resolved photoelectron spectroscopy [1] suggested altered dynamics in DMF relative to furan but lacked direct structural sensitivity. Here, gas-phase MeV ultrafast electron diffraction simultaneously probes electronic population dynamics (inelastic scattering) and nuclear dynamics (elastic scattering). We observe formation of a puckered intermediate within 250 fs, followed by delayed ring opening after 250-500 fs, while excited-state populations persist for the first ∼400 fs. In contrast to furan, where ring opening occurs within 50 fs and dominates (puckering:opening ratio of 80:20), DMF shows inverted branching (20:80). We conclude with a new high-repetition-rate gas-phase keV UED platform in Berlin.

[1] O. Schalk et al., Phys. Chem. Chem. Phys. 19 084303 (2018).

Keywords: Coupled electronic-nuclear dynamics; ultrafast electron diffraction; femtochemistry; gas-phase photochemistry