Mainz 2026 – scientific programme
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MO: Fachverband Molekülphysik
MO 27: Molecular Spectroscopy II
MO 27.7: Talk
Thursday, March 5, 2026, 16:00–16:15, P 204
Ultrafast dissociation dynamics of HCO+ — •Anastasia Andreeva1, Simon Reinwardt1, Julius Schwarz1, B. Michel Döhring2,3, Maria Tatsch2, David Macaluso6, Alfred Müller2, Nicolas Solem5, Roland Thissen5, Florian Trinter4, Stefan Schippers2,3, and Michael Martins1 — 1Institut für Experimentalphysik, Universität Hamburg — 2Justus-Liebig-Universität, Gießen — 3Helmholtz Forschungsakademie Hessen für FAIR (HFHF), GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt — 4Fritz-Haber-Institut, Berlin — 5Institut de Chimie Physique, Université Paris-Saclay, Orsay — 6Department of Physics and Astronomy, University of Montana, Missoula
Ultrafast dissociation of molecules often results in radicals or ionic products. One of these products can be H or H+, which is the key actor in many chemical reactions that rely on proton transfer. However, due to the difficulty of determining the electron densities on the atomic and femtosecond scale, the study of dissociation dynamics is experimentally difficult to achieve and requires either ultrafast pump-probe experiments or indirect investigation of dissociation products. Here we present the latter technique of obtaining information on proton dissociation after an inner-shell excitation in HCO+ by resolving the kinetic energy release of the ionic fragments using the Photon-Ion Spectrometer (PIPE) at PETRA III. We used soft X-ray radiation to perform site-specific photoexcitation in HCO+ and found an unexpected dissociation behavior at the C 1s → π* resonance. Finally, we described it by a theoretical calculation based on full-CI.
Keywords: soft x-ray; molecular ions; dissociation dynamics; kinetic energy release; proton dynamics