Bonn 2025 – scientific programme
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MO: Fachverband Molekülphysik
MO 13: Ultrafast Dynamics II
MO 13.1: Talk
Wednesday, March 12, 2025, 11:00–11:15, HS XVI
Photo-induced structural dynamics of thymine with ultrafast electron diffraction — •Xiaojun Wang1, Jackson Lederer2, Dennis Mayer1, Fabiano Lever1, Pedro Nunes2, Yusong Liu3, Surjendu Bhattacharyya3, Nikhil Pachisia2, Xinxin Cheng3, Tianzhe Xu3, Stephen Weathersby3, Randy Lemons3, Patrick Kramer3, Philipp Lenzen3, Ming-Fu Lin3, Kirk Larsen3, Fuhao Ji3, Robert England3, Christina Hampton3, Brian Kaufman3, Alice Green3, Alexander Reid3, Todd Martinez3,4, Thomas Wolf3, Martin Centurion2, and Markus Guehr1,5 — 1Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, USA — 3SLAC National Accelerator Laboratory, Menlo Park, USA — 4Department of Chemistry, Stanford University, Stanford, USA — 5Institute of Physical Chemistry, University of Hamburg, Hamburg, Germany
The photoprotection mechanism of thymine involves complex relaxation dynamics, where energy from photoexcitation is converted into vibrational energy through radiationless transitions. Previous studies have indicated that isolated thymine molecules undergo 1ππ* → 1nπ* internal conversion within 100 femtoseconds (fs), followed by the intersystem crossing from 1nπ* to the triplet state within 10 picoseconds (ps). However, the nuclear dynamics accompanying the transitions have not been experimentally resolved. Here we present a direct observation of the ultrafast nuclear motions using ultrafast electron diffraction, on the fs timescale and sub-Ångstrom resolution.
Keywords: Ultrafast electron diffraction; Ultrafast structural dynamics; Photochemistry; Excited state dynamics; Conical intersection