Mainz 2026 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 13: Poster – Ultrafast Electronic Dynamics
MO 13.1: Poster
Dienstag, 3. März 2026, 17:00–19:00, Philo 1. OG
Time-resolved photoelectron spectroscopy of acetone using few-femtosecond pulses — Kate Robertson1,2,3, Ammar B. Wahid1, •Aurelien Sanchez1,2,3, Sergey Riabchuk1,2,3, Lorenzo Colaizzi1, Erik Månsson1, Terence Mullins1,2,3, Vincent Wanie1, and Francesca Calegari1,2,3 — 1Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron, Germany — 2The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Germany — 3Physics Department, Universität Hamburg
Few-femtosecond ultraviolet (UV) pulses are essential for tracking electron motion in electronically excited neutral molecules. Because UV light drives many key photochemical and biological reactions, the ability to generate pulses of such brevity opens a path to probing these processes with unprecedented temporal sensitivity. In this work, we report a time-resolved photoelectron spectroscopy study of acetone using 2.1-fs transform-limited UV pump pulses together with near-infrared probe pulses, yielding an overall temporal resolution of 5.6 fs. Acetone exhibits intricate Rydberg couplings that strongly shape its excited-state behavior. While earlier time-resolved measurements have examined these dynamics, their temporal resolution was insufficient to resolve processes evolving on a few- to tens-of-femtoseconds timescale. Our measurements uncover strong electronic and vibrational coherences and provide clear evidence for rapid relaxation into the ππ* state. We observe a slow oscillation of 24 fs persisting for roughly 100 fs in the photoelectron signal, alongside a faster 3.2 fs modulation, which may reflect the presence of an electronic coherence.
Keywords: excited rydberg states; electronic coherences; TRPES